def blockIndentation(block):
            text = block.text()
            return text[:len(text) - len(text.lstrip())]
def __init__(self, saddr, gaddr, glen):
        self.saddr = saddr
        self.gaddr = gaddr
        self.glen = glen
        if ip_address(self.saddr).version != \
           ip_address(self.gaddr).version:
            raise ValueError('Source and group addresses must be of the '
                             'same address family.')