Fix undefined name

Author: larshum

thealgorithms/graphs/Directed_and_Undirected_Weighted_Graph.py

@@ -153,6 +153,7 @@ def cycle_nodes(self):
 		indirect_parents = []
 		ss = s
 		anticipating_nodes = set()
+		on_the_way_back = False
 
 		while True:
 			# check if there is any non isolated nodes
@@ -200,6 +201,7 @@ def has_cycle(self):
 		indirect_parents = []
 		ss = s
 		anticipating_nodes = set()
+		on_the_way_back = False
 
 		while True:
 			# check if there is any non isolated nodes
@@ -368,6 +370,7 @@ def cycle_nodes(self):
 		indirect_parents = []
 		ss = s
 		anticipating_nodes = set()
+		on_the_way_back = False
 
 		while True:
 			# check if there is any non isolated nodes
@@ -415,6 +418,7 @@ def has_cycle(self):
 		indirect_parents = []
 		ss = s
 		anticipating_nodes = set()
+		on_the_way_back = False
 
 		while True:
 			# check if there is any non isolated nodes