In [ ]:

    

class stack(object):
    '''Class to implement stack data structure with the following methods:
        -push(element)
        -pop()'''
    def __init__(self):
        self.s = []
    def push(self,elem):
        self.s.append(elem)
    def pop(self):
        p =  self.s[-1]
        del self.s[-1]
        return p
    def empty(self):
        if len(self.s)==0:
            return True
        else:
            return False
def parenMismatch(expression):
    '''Function to return True in case of parenthesis mismatch in an expression and False otherwise'''
    s = stack()
    for i in xrange(len(expression)):
        if expression[i]=='(':
            s.push('(')
        elif expression[i]==')':
            s.pop()
    if s.empty():
        return False
    else:
        return True