mark unreachable code with a TODO comment

Author: Hasenn

graphs/directed_and_undirected_(weighted)_graph.py

@@ -226,7 +226,9 @@ def has_cycle(self):
                                 break
                             else:
                                 return True
-                                anticipating_nodes.add(stack[len_stack_minus_one])
+                                # TODO:The following code is unreachable.
+                                anticipating_nodes.add(
+                                    stack[len_stack_minus_one])
                                 len_stack_minus_one -= 1
                     if visited.count(node[1]) < 1:
                         stack.append(node[1])
@@ -453,7 +455,10 @@ def has_cycle(self):
                                 break
                             else:
                                 return True
-                                anticipating_nodes.add(stack[len_stack_minus_one])
+                                # TODO: the following code is unreachable
+                                # is this meant to be called in the else ?
+                                anticipating_nodes.add(
+                                    stack[len_stack_minus_one])
                                 len_stack_minus_one -= 1
                     if visited.count(node[1]) < 1:
                         stack.append(node[1])