addiing blanklines between </dl> and the examples in docstrings

Author: mmatera

pymathics/graph/base.py

@@ -1448,6 +1448,7 @@ class VertexIndex(_NetworkXBuiltin):
       <dd> gives the integer index of the vertex 'v' in the\
        graph 'g'.
     </dl>
+
     >> a=.;
     >> VertexIndex[{c <-> d, d <-> a}, a]
      = 3

pymathics/graph/components.py

@@ -71,6 +71,7 @@ def eval(
 #       <dt>'FindHamiltonianPath[$g$]'
 #       <dd>returns a Hamiltonian path in the given tournament graph.
 #       </dl>
+#
 #     """
 #     def eval_(self, graph, expression, evaluation: Evaluation, options):
 #         "FindHamiltonianPath[graph_, OptionsPattern[FindHamiltonPath]]"

pymathics/graph/parametric.py

@@ -469,6 +469,7 @@ class KaryTree(_NetworkXBuiltin):
       <dt>'KaryTree[$n$, $k$]'
       <dd>Creates $k$-ary tree with $n$ vertices.
     </dl>
+
     >> KaryTree[10]
      = -Graph-
 
@@ -552,6 +553,7 @@ class PathGraph(_NetworkXBuiltin):
       <dd>Returns a Graph with a path with vertices $v_i$ and \
       edges between $v-i$ and $v_i+1$ .
     </dl>
+
     >> PathGraph[{1, 2, 3}]
      = -Graph-
     """

pymathics/graph/structured.py

@@ -21,6 +21,7 @@ class PathGraph(_NetworkXBuiltin):
       <dt>'PathGraph[{$v_1$, $v_2$, ...}]'
       <dd>Returns a Graph with a path with vertices $v_i$ and edges between $v-i$ and $v_i+1$ .
     </dl>
+
     >> PathGraph[{1, 2, 3}]
      = -Graph-
     """