Fix '__bool__' method (TheAlgorithms#735)

SemeniukMN · ashwek · commit 8e67ac3b7672 · 2019-03-10T07:40:29.000+05:30
The method returns the truth when the stack is empty
diff --git a/data_structures/stacks/stack.py b/data_structures/stacks/stack.py
@@ -17,7 +17,7 @@ def __init__(self, limit=10):
         self.limit = limit
 
     def __bool__(self):
-        return not bool(self.stack)
+        return bool(self.stack)
 
     def __str__(self):
         return str(self.stack)
