def serialize(self):
    r = b''
    r += struct.pack('<B', self.filter_type)
    r += ser_uint256(self.block_hash)
    r += ser_string(self.filter_data)
    return r
def serialize(self):
    r = b
    r += struct.pack('<B', self.filter_type)
    r += ser_uint256(self.block_hash)
    r += ser_string(self.filter_data)
    return r