# use a stack to check whether parentheses are balanced
import stack

def balanced_delimiters(s):
    ''' (str) -> bool

    Return whether the brackets in string s are balanced.

    Assume: Only delimiters are brackets
    >>> balanced_delimiters('[({])}')
    False
    >>> balanced_delimiters('[({})]]')
    False
    >>> balanced_delimiters('[[]')
    False
    >>> balanced_delimiters('[(){}]')
    True
    '''
    st = stack.Stack()
    for c in s:
        if not c in '(){}[]':
            pass
        elif c in '({[':
            st.push(c)
        # now must have c in ')}]'
        elif not st.is_empty():
            c2 = st.pop()
            if ((c == ')' and not c2 == '(') or
                (c == '}' and not c2 == '{') or
                (c == ']' and not c2 == '[')):
                return False
        else: # prematurely empty stack!
            return False
    return st.is_empty() # better be empty at the end


if __name__ == '__main__':
    import doctest
    doctest.testmod()