Fixing lgtm issue in basic graphs (#1141)

* Added print function into matrix_multiplication_addition.py and removed blank space in data_structures/binary tree directory

* Removed .vs/ folder per #893

* Rename matrix_multiplication_addition.py to matrix_operation.py

* Fixing lgtm issue in basic_graphs per ##1024

* Fixed lgtm issue per @cclauss recommendation in #1024

Author: qckzr

Diff for: graphs/basic_graphs.py

@@ -128,7 +128,9 @@ def dijk(G, s):
 from collections import deque
 
 
-def topo(G, ind=None, Q=[1]):
+def topo(G, ind=None, Q=None):
+    if Q is None:
+        Q = [1]
     if ind is None:
         ind = [0] * (len(G) + 1)  # SInce oth Index is ignored
         for u in G: