CODE EXAMPLE FOR PYTHON

python stack class

class Stack():
    def __init__(self, list = []):
        self._stack = list
        
    def push(self, item):
        if(hasattr(item, "__getitem__")):
            self._stack.extend(item)        
        else:
            self._stack.append(item)
        
    def isEmpty(self):
        return not self._stack
    
    def pop(self):
        if(self.isEmpty()):
            return None
        return self._stack.pop()
    
    def peek(self):
        if(self.isEmpty()):
            return None
        return self._stack[-1]
    
    def size(self):
        return len(self._stack)