def remove_parenthesis2(string):
    """Remove parentheses and text within them.
    For nested parentheses, removes the whole thing.
    """
    ret = ''
    skip_c = 0
    for c in string:
        if c == '(':
            skip_c += 1
        elif c == ')' and skip_c > 0:
            skip_c -= 1
        elif skip_c == 0:
            ret += c
    return ret