Reverse the strings contained in each pair of matching parentheses.

reverseParentheses.py

"""
Reverse the strings contained in each pair of matching parentheses, starting from the innermost pair.
The results string should not contain any parentheses.
"""
def reverseParentheses(s):
    stack = [""]

    for letter in s:
        if letter == "(":
            stack.append("")
        elif letter == ")":
            word = stack.pop()
            stack[-1]+= word[::-1]
        else:
            stack[-1]+= letter
    return stack[0]