Ticket #14805: trac_14805.patch

doc/en/reference/graphs/index.rst

@@ -38 +38 @@
    sage/graphs/base/sparse_graph
    sage/graphs/base/dense_graph
    sage/graphs/base/static_sparse_graph
+   sage/graphs/base/graph_backends
 
 Hypergraphs
 -----------

sage/graphs/base/graph_backends.py

@@ -20 +20 @@
     extensions of this class.  Note, this graph has a number of placeholder
     functions, so the doctests are rather silly.
 
-    DOCTEST:
+    TESTS::
+
         sage: import sage.graphs.base.graph_backends
 
     """
@@ -31 +32 @@
         """
         Add an edge (u,v) to self, with label l.  If directed is True, this is
         interpreted as an arc from u to v.
-        
-        INPUT:
-            u,v:      vertices
-            l:        edge label
-            directed: boolean
-        
-        DOCTEST:
+
+        INPUT::
+
+        - ``u,v`` -- vertices
+        - ``l`` -- edge label
+        - ``directed`` -- boolean
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.GenericGraphBackend()
             sage: G.add_edge(1,2,'a',True)
             Traceback (most recent call last):
@@ -49 +52 @@
         """
         Add a sequence of edges to self.  If directed is True, these are
         interpreted as arcs.
-        
+
         INPUT:
-            edges:    iterator
-            directed: boolean
-        
-        DOCTEST:
+
+        - ``edges`` -- list/iterator of edges to be added.
+
+        - ``directed`` -- boolean
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.GenericGraphBackend()
             sage: G.add_edges([],True)
             Traceback (most recent call last):
             ...
             NotImplementedError
-        """ 
+        """
         raise NotImplementedError()
+
     def add_vertex(self, name):
         """
         Add a labelled vertex to self.
-        
+
         INPUT:
 
         - ``name`` -- vertex label
-        
+
         OUTPUT:
 
-        If ``name``=``None``, the new vertex name is returned, ``None`` otherwise.
+        If ``name=None``, the new vertex name is returned, ``None`` otherwise.
 
-        DOCTEST:
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.GenericGraphBackend()
             sage: G.add_vertex(0)
             Traceback (most recent call last):
             ...
             NotImplementedError
-        """ 
+        """
         raise NotImplementedError()
     def add_vertices(self, vertices):
         """
         Add labelled vertices to self.
-        
+
         INPUT:
 
-        - ``vertices``: iterator of vertex labels. A new label is created, used and returned in
-          the output list for all ``None`` values in ``vertices``.
+        - ``vertices`` -- iterator of vertex labels. A new label is created,
+          used and returned in the output list for all ``None`` values in
+          ``vertices``.
 
         OUTPUT:
 
@@ -103 +112 @@
             Traceback (most recent call last):
             ...
             NotImplementedError
-        """ 
+        """
         raise NotImplementedError()
     def degree(self, v, directed):
         """
         Returns the total number of vertices incident to v.
-        
+
         INPUT:
-            v:       a vertex label
-            directed: boolean
+
+        - ``v`` -- a vertex label
+        - ``directed`` -- boolean
+
         OUTPUT:
+
             degree of v
-            
-        DOCTEST:
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.GenericGraphBackend()
             sage: G.degree(1, False)
             Traceback (most recent call last):
             ...
             NotImplementedError
-        """ 
+        """
         raise NotImplementedError()
     def del_edge(self, u, v, l, directed):
         """
         Deletes the edge (u,v) with label l.
 
         INPUT:
-            u,v:      vertices
-            l:        edge label
-            directed: boolean
-        
-        DOCTEST:
+
+        - ``u,v`` -- vertices
+        - ``l`` -- edge label
+        - ``directed`` -- boolean
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.GenericGraphBackend()
             sage: G.del_edge(1,2,'a',True)
             Traceback (most recent call last):
             ...
             NotImplementedError
-        """ 
+        """
         raise NotImplementedError()
     def del_vertex(self, v):
         """
         Delete a labelled vertex in self.
-        
+
         INPUT:
-            v: vertex label
-        
-        DOCTEST:
+
+        - ``v`` -- vertex label
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.GenericGraphBackend()
             sage: G.del_vertex(0)
             Traceback (most recent call last):
             ...
             NotImplementedError
-        """ 
+        """
         raise NotImplementedError()
     def del_vertices(self, vertices):
         """
         Delete labelled vertices in self.
-        
+
         INPUT:
-            vertices: iterator of vertex labels
-        
-        DOCTEST:
+
+        - ``vertices`` -- iterator of vertex labels
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.GenericGraphBackend()
             sage: G.del_vertices([1,2,3])
             Traceback (most recent call last):
             ...
             NotImplementedError
-        """ 
+        """
         raise NotImplementedError()
     def get_edge_label(self, u, v):
         """
         Returns the edge label of (u,v).
 
         INPUT:
-            u,v: vertex labels
-        
+
+        - ``u,v`` -- vertex labels
+
         OUTPUT:
+
             label of (u,v)
-        
-        DOCTEST:
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.GenericGraphBackend()
             sage: G.get_edge_label(1,2)
             Traceback (most recent call last):
             ...
             NotImplementedError
-        """ 
+        """
         raise NotImplementedError()
     def has_edge(self, u, v, l):
         """
         True if self has an edge (u,v) with label l.
 
         INPUT:
-            u,v: vertex labels
-            l: label
-        
+
+        - ``u,v`` -- vertex labels
+        - ``l`` -- label
+
         OUTPUT:
+
             boolean
-        
-        DOCTEST:
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.GenericGraphBackend()
             sage: G.has_edge(1,2,'a')
             Traceback (most recent call last):
             ...
             NotImplementedError
-        """ 
+        """
         raise NotImplementedError()
     def has_vertex(self, v):
         """
         True if self has a vertex with label v.
 
         INPUT:
-            v: vertex label
-        
+
+        - ``v`` -- vertex label
+
         OUTPUT:
             boolean
-        
-        DOCTEST:
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.GenericGraphBackend()
             sage: G.has_vertex(0)
             Traceback (most recent call last):
             ...
             NotImplementedError
-        """ 
+        """
         raise NotImplementedError()
     def iterator_edges(self, vertices, labels):
         """
         Iterate over the edges incident to a sequence of vertices. Edges are
         assumed to be undirected.
-        
+
         INPUT:
-            vertices:     a list of vertex labels
-            labels:       boolean
-            
+
+        - ``vertices`` -- a list of vertex labels
+        - ``labels`` -- boolean
+
         OUTPUT:
-            a generator which yields edges, with or without labels 
+
+            a generator which yields edges, with or without labels
             depending on the labels parameter.
-            
-        DOCTEST:
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.GenericGraphBackend()
             sage: G.iterator_edges([],True)
             Traceback (most recent call last):
@@ -249 +279 @@
     def iterator_in_edges(self, vertices, labels):
         """
         Iterate over the incoming edges incident to a sequence of vertices.
-        
+
         INPUT:
-            vertices:     a list of vertex labels
-            labels:       boolean
-            
+
+        - ``vertices`` -- a list of vertex labels
+        - ``labels`` -- boolean
+
         OUTPUT:
-            a generator which yields edges, with or without labels 
+            a generator which yields edges, with or without labels
             depending on the labels parameter.
-            
-        DOCTEST:
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.GenericGraphBackend()
             sage: G.iterator_in_edges([],True)
             Traceback (most recent call last):
@@ -269 +301 @@
     def iterator_out_edges(self, vertices, labels):
         """
         Iterate over the outbound edges incident to a sequence of vertices.
-        
+
         INPUT:
-            vertices:     a list of vertex labels
-            labels:       boolean
-            
+
+        - ``vertices`` -- a list of vertex labels
+        - ``labels`` -- boolean
+
         OUTPUT:
-            a generator which yields edges, with or without labels 
+
+            a generator which yields edges, with or without labels
             depending on the labels parameter.
-            
-        DOCTEST:
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.GenericGraphBackend()
             sage: G.iterator_out_edges([],True)
             Traceback (most recent call last):
@@ -289 +324 @@
     def iterator_nbrs(self, v):
         """
         Iterate over the vertices adjacent to v.
-        
+
         INPUT:
-            v: vertex label
-            
+
+        - ``v`` -- vertex label
+
         OUTPUT:
+
             a generator which yields vertex labels
-            
-        DOCTEST:
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.GenericGraphBackend()
             sage: G.iterator_nbrs(0)
             Traceback (most recent call last):
@@ -308 +346 @@
         """
         Iterate over the vertices u such that the edge (u,v) is in self
         (that is, predecessors of v).
-        
+
         INPUT:
-            v: vertex label
-            
+
+        - ``v`` -- vertex label
+
         OUTPUT:
+
             a generator which yields vertex labels
-            
-        DOCTEST:
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.GenericGraphBackend()
             sage: G.iterator_in_nbrs(0)
             Traceback (most recent call last):
@@ -327 +368 @@
         """
         Iterate over the vertices u such that the edge (v,u) is in self
         (that is, successors of v).
-        
+
         INPUT:
-            v: vertex label
-            
+
+        - ``v`` -- vertex label
+
         OUTPUT:
+
             a generator which yields vertex labels
-            
-        DOCTEST:
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.GenericGraphBackend()
             sage: G.iterator_out_nbrs(0)
             Traceback (most recent call last):
@@ -345 +389 @@
     def iterator_verts(self, verts):
         """
         Iterate over the vertices v with labels in verts.
-        
+
         INPUT:
-            vertex: vertex labels
-            
+
+        - ``vertex`` -- vertex labels
+
         OUTPUT:
+
             a generator which yields vertices
-            
-        DOCTEST:
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.GenericGraphBackend()
             sage: G.iterator_verts(0)
             Traceback (most recent call last):
@@ -360 +407 @@
             NotImplementedError
         """
         raise NotImplementedError()
-    def loops(self, new):
+
+    def loops(self, new=None):
         """
-        Get/set whether or not self allows loops.        
-        
+        Get/set whether or not self allows loops.
+
         INPUT:
-            new: boolean or None
-        
-        DOCTEST:
+
+        - ``new`` -- can be a boolean (in which case it sets the value) or
+          ``None``, in which case the current value is returned. It is set to
+          ``None`` by default.
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.GenericGraphBackend()
             sage: G.loops(True)
             Traceback (most recent call last):
@@ -379 +431 @@
             NotImplementedError
         """
         raise NotImplementedError()
-    def multiple_edges(self, new):
+    def multiple_edges(self, new=None):
         """
         Get/set whether or not self allows multiple edges.
-        
+
         INPUT:
-            new: boolean or None
-        
-        DOCTEST:
+
+        - ``new`` -- can be a boolean (in which case it sets the value) or
+          ``None``, in which case the current value is returned. It is set to
+          ``None`` by default.
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.GenericGraphBackend()
             sage: G.multiple_edges(True)
             Traceback (most recent call last):
@@ -398 +454 @@
             NotImplementedError
         """
         raise NotImplementedError()
-    def name(self, new):
+    def name(self, new=None):
         """
         Get/set name of self.
-        
+
         INPUT:
-            new: string or None
-        
-        DOCTEST:
+
+        - ``new`` -- can be a string (in which case it sets the value) or
+          ``None``, in which case the current value is returned. It is set to
+          ``None`` by default.
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.GenericGraphBackend()
             sage: G.name("A Generic Graph")
             Traceback (most recent call last):
@@ -420 +480 @@
     def num_edges(self, directed):
         """
         The number of edges in self
-        
+
         INPUT:
-            directed: boolean
-        
-        DOCTEST:
+
+        - ``directed`` -- boolean
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.GenericGraphBackend()
             sage: G.num_edges(True)
             Traceback (most recent call last):
@@ -439 +501 @@
     def num_verts(self):
         """
         The number of vertices in self
-        
-        DOCTEST:
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.GenericGraphBackend()
             sage: G.num_verts()
             Traceback (most recent call last):
@@ -451 +514 @@
     def relabel(self, perm, directed):
         """
         Relabel the vertices of self by a permutation.
+
         INPUT:
-            perm:     permutation
-            directed: boolean
-        
-        DOCTEST:
+
+        - ``perm`` -- permutation
+        - ``directed`` -- boolean
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.GenericGraphBackend()
             sage: G.relabel([],False)
             Traceback (most recent call last):
@@ -466 +532 @@
     def set_edge_label(self, u, v, l, directed):
         """
         Label the edge (u,v) by l.
-        
+
         INPUT:
-            u,v:      vertices
-            l:        edge label
-            directed: boolean
-        
-        DOCTEST:
+
+        - ``u,v`` -- vertices
+        - ``l`` -- edge label
+        - ``directed`` -- boolean
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.GenericGraphBackend()
             sage: G.set_edge_label(1,2,'a',True)
             Traceback (most recent call last):
             ...
             NotImplementedError
-        """        
+        """
         raise NotImplementedError()
 
 class NetworkXGraphDeprecated(SageObject):
     """
     Class for unpickling old networkx.XGraph formats
 
-    DOCTEST::
+    TESTS::
 
         sage: from sage.graphs.base.graph_backends import NetworkXGraphDeprecated as NXGD
         sage: X = NXGD()
         doctest:...
-        
+
     """
 
     def __init__(self):
@@ -557 +625 @@
     """
     Class for unpickling old networkx.XDiGraph formats
 
-    DOCTEST:
+    TESTS::
+
         sage: import sage.graphs.base.graph_backends
     """
 
@@ -629 +698 @@
     """
     A wrapper for NetworkX as the backend of a graph.
 
-    DOCTEST:
+    TESTS::
+
         sage: import sage.graphs.base.graph_backends
 
     """
@@ -639 +709 @@
     def __init__(self, N=None):
         """
         Initialize the backend with NetworkX graph N.
-        
-        DOCTEST:
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.NetworkXGraphBackend()
             sage: G.iterator_edges([],True)
             <generator object iterator_edges at ...>
@@ -659 +730 @@
         """
         Add an edge (u,v) to self, with label l.  If directed is True, this is
         interpreted as an arc from u to v.
-        
+
         INPUT:
-            u,v:      vertices
-            l:        edge label
-            directed: boolean
-        
-        DOCTEST:
+
+        - ``u,v`` -- vertices
+        - ``l`` -- edge label
+        - ``directed`` -- boolean
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.NetworkXGraphBackend()
             sage: G.add_edge(1,2,'a',True)
         """
@@ -687 +760 @@
         """
         Add a sequence of edges to self.  If directed is True, these are
         interpreted as arcs.
-        
+
         INPUT:
-            edges:    iterator
-            directed: boolean
-        
-        DOCTEST:
+
+        - ``edges`` -- list/iterator of edges to be added.
+        - ``directed`` -- boolean
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.NetworkXGraphBackend()
             sage: G.add_edges([],True)
         """
@@ -707 +782 @@
     def add_vertex(self, name):
         """
         Add a labelled vertex to self.
-        
+
         INPUT:
 
         - ``name``: vertex label
-        
+
         OUTPUT:
 
-        If ``name``=``None``, the new vertex name is returned. ``None`` otherwise.
+        If ``name=None``, the new vertex name is returned. ``None`` otherwise.
 
-        DOCTEST:
+        TESTS::
 
             sage: G = sage.graphs.base.graph_backends.NetworkXGraphBackend()
             sage: G.add_vertex(0)
@@ -785 +860 @@
     def degree(self, v, directed):
         """
         Returns the total number of vertices incident to v.
-        
+
         INPUT:
-            v:       a vertex label
-            directed: boolean
+
+        - ``v`` -- a vertex label
+        - ``directed`` -- boolean
+
         OUTPUT:
+
             degree of v
-            
-        DOCTEST:
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.NetworkXGraphBackend()
             sage: G.add_vertices(range(3))
             sage: G.degree(1, False)
@@ -810 +889 @@
         Deletes the edge (u,v) with label l.
 
         INPUT:
-            u,v:      vertices
-            l:        edge label
-            directed: boolean
-        
-        DOCTEST:
+
+        - ``u,v`` -- vertices
+        - ``l`` -- edge label
+        - ``directed`` -- boolean
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.NetworkXGraphBackend()
             sage: G.del_edge(1,2,'a',True)
         """
@@ -840 +921 @@
     def del_vertex(self, v):
         """
         Delete a labelled vertex in self.
-        
+
         INPUT:
-            v: vertex label
-        
-        DOCTEST:
+
+        - ``v`` -- vertex label
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.NetworkXGraphBackend()
             sage: G.del_vertex(0)
             Traceback (most recent call last):
@@ -861 +944 @@
     def del_vertices(self, vertices):
         """
         Delete labelled vertices in self.
-        
+
         INPUT:
-            vertices: iterator of vertex labels
-        
-        DOCTEST:
+
+        - ``vertices`` -- iterator of vertex labels
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.NetworkXGraphBackend()
             sage: G.del_vertices([1,2,3])
             Traceback (most recent call last):
@@ -885 +970 @@
         Returns the edge label of (u,v).
 
         INPUT:
-            u,v: vertex labels
-        
+
+        - ``u,v`` -- vertex labels
+
         OUTPUT:
             label of (u,v)
-        
-        DOCTEST:
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.NetworkXGraphBackend()
             sage: G.get_edge_label(1,2)
             Traceback (most recent call last):
@@ -918 +1005 @@
         True if self has an edge (u,v) with label l.
 
         INPUT:
-            u,v: vertex labels
-            l: label
-        
+
+        - ``u,v`` -- vertex labels
+        - ``l`` -- label
+
         OUTPUT:
             boolean
-        
-        DOCTEST:
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.NetworkXGraphBackend()
             sage: G.has_edge(1,2,'a')
             False
@@ -948 +1037 @@
         True if self has a vertex with label v.
 
         INPUT:
-            v: vertex label
-        
+
+        - ``v`` -- vertex label
+
         OUTPUT:
             boolean
-        
-        DOCTEST:
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.NetworkXGraphBackend()
             sage: G.has_vertex(0)
             False
@@ -969 +1060 @@
         """
         Iterate over the edges incident to a sequence of vertices. Edges are
         assumed to be undirected.
-        
+
         INPUT:
-            vertices:     a list of vertex labels
-            labels:       boolean
-            
+
+        - ``vertices`` -- a list of vertex labels
+        - ``labels`` -- boolean
+
         OUTPUT:
-            a generator which yields edges, with or without labels 
+            a generator which yields edges, with or without labels
             depending on the labels parameter.
-            
-        DOCTEST:
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.NetworkXGraphBackend()
             sage: G.iterator_edges([],True)
             <generator object iterator_edges at ...>
@@ -1019 +1112 @@
     def iterator_in_edges(self, vertices, labels):
         """
         Iterate over the incoming edges incident to a sequence of vertices.
-        
+
         INPUT:
-            vertices:     a list of vertex labels
-            labels:       boolean
-            
+
+        - ``vertices`` -- a list of vertex labels
+        - ``labels`` -- boolean
+
         OUTPUT:
-            a generator which yields edges, with or without labels 
+            a generator which yields edges, with or without labels
             depending on the labels parameter.
-            
-        DOCTEST:
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.NetworkXGraphBackend()
             sage: i = G.iterator_in_edges([],True)
         """
@@ -1067 +1162 @@
     def iterator_out_edges(self, vertices, labels):
         """
         Iterate over the outbound edges incident to a sequence of vertices.
-        
+
         INPUT:
-            vertices:     a list of vertex labels
-            labels:       boolean
-            
+
+        - ``vertices`` -- a list of vertex labels
+        - ``labels`` -- boolean
+
         OUTPUT:
-            a generator which yields edges, with or without labels 
+            a generator which yields edges, with or without labels
             depending on the labels parameter.
-            
-        DOCTEST:
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.NetworkXGraphBackend()
             sage: i = G.iterator_out_edges([],True)
         """
@@ -1096 +1193 @@
     def iterator_nbrs(self, v):
         """
         Iterate over the vertices adjacent to v.
-        
+
         INPUT:
-            v: vertex label
-            
+
+        - ``v`` -- vertex label
+
         OUTPUT:
             a generator which yields vertex labels
-            
-        DOCTEST:
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.NetworkXGraphBackend()
             sage: G.add_vertex(0)
             sage: G.iterator_nbrs(0)
@@ -1120 +1219 @@
         """
         Iterate over the vertices u such that the edge (u,v) is in self
         (that is, predecessors of v).
-        
+
         INPUT:
-            v: vertex label
-            
+
+        - ``v`` -- vertex label
+
         OUTPUT:
             a generator which yields vertex labels
-            
-        DOCTEST:
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.NetworkXGraphBackend()
             sage: G.iterator_in_nbrs(0)
             Traceback (most recent call last):
@@ -1145 +1246 @@
         """
         Iterate over the vertices u such that the edge (v,u) is in self
         (that is, successors of v).
-        
+
         INPUT:
-            v: vertex label
-            
+
+        - ``v`` -- vertex label
+
         OUTPUT:
             a generator which yields vertex labels
-            
-        DOCTEST:
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.NetworkXGraphBackend()
             sage: G.iterator_out_nbrs(0)
             Traceback (most recent call last):
@@ -1169 +1272 @@
     def iterator_verts(self, verts):
         """
         Iterate over the vertices v with labels in verts.
-        
+
         INPUT:
-            vertex: vertex labels
-            
+
+        - ``vertex`` -- vertex labels
+
         OUTPUT:
             a generator which yields vertices
-            
-        DOCTEST:
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.NetworkXGraphBackend()
             sage: G.iterator_verts(0)
             <generator object bunch_iter at ...>
@@ -1188 +1293 @@
 
         return self._nxg.nbunch_iter(verts)
 
-    def loops(self, new):
+    def loops(self, new=None):
         """
-        Get/set whether or not self allows loops.        
-        
+        Get/set whether or not self allows loops.
+
         INPUT:
-            new: boolean or None
-        
-        DOCTEST:
+
+        - ``new`` -- can be a boolean (in which case it sets the value) or
+          ``None``, in which case the current value is returned. It is set to
+          ``None`` by default.
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.NetworkXGraphBackend()
             sage: G.loops(True)
             sage: G.loops(None)
@@ -1208 +1317 @@
         else:
             self._loops = False
 
-    def multiple_edges(self, new):
+    def multiple_edges(self, new=None):
         """
         Get/set whether or not self allows multiple edges.
-        
+
         INPUT:
-            new: boolean or None
-        
-        DOCTEST:
+
+        - ``new`` -- can be a boolean (in which case it sets the value) or
+          ``None``, in which case the current value is returned. It is set to
+          ``None`` by default.
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.NetworkXGraphBackend()
             sage: G.multiple_edges(True)
             sage: G.multiple_edges(None)
@@ -1242 +1355 @@
             else:
                 self._nxg = Graph(self._nxg)
 
-    def name(self, new):
+    def name(self, new=None):
         """
         Get/set name of self.
-        
+
         INPUT:
-            new: string or None
-        
-        DOCTEST:
+
+        - ``new`` -- can be a string (in which case it sets the value) or
+          ``None``, in which case the current value is returned. It is set to
+          ``None`` by default.
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.NetworkXGraphBackend()
             sage: G.name("A NetworkX Graph")
             sage: G.name(None)
@@ -1267 +1384 @@
     def num_edges(self, directed):
         """
         The number of edges in self
-        
+
         INPUT:
-            directed: boolean
-        
-        DOCTEST:
+
+        - ``directed`` -- boolean
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.NetworkXGraphBackend()
             sage: G.num_edges(True)
             0
@@ -1288 +1407 @@
     def num_verts(self):
         """
         The number of vertices in self
-        
-        DOCTEST:
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.NetworkXGraphBackend()
             sage: G.num_verts()
             0
@@ -1304 +1424 @@
     def relabel(self, perm, directed):
         """
         Relabel the vertices of self by a permutation.
+
         INPUT:
-            perm:     permutation
-            directed: boolean
-        
-        DOCTEST:
+
+        - ``perm`` -- permutation
+        - ``directed`` -- boolean
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.NetworkXGraphBackend()
             sage: G.relabel([],False)
         """
@@ -1356 +1479 @@
     def set_edge_label(self, u, v, l, directed):
         """
         Label the edge (u,v) by l.
-        
+
         INPUT:
-            u,v:      vertices
-            l:        edge label
-            directed: boolean
-        
-        DOCTEST:
+
+        - ``u,v`` -- vertices
+        - ``l`` -- edge label
+        - ``directed`` -- boolean
+
+        TESTS::
+
             sage: G = sage.graphs.base.graph_backends.NetworkXGraphBackend()
             sage: G.set_edge_label(1,2,'a',True)
         """