return encoded representation

def binary(self):
        """
        return encoded representation
        """
        creation_size = len(self.creation)
        if creation_size == 1:
            return (
                b_chr(_TAG_PID_EXT) +
                self.node.binary() + self.id + self.serial + self.creation
            )
        elif creation_size == 4:
            return (
                b_chr(_TAG_NEW_PID_EXT) +
                self.node.binary() + self.id + self.serial + self.creation
            )
        else:
            raise OutputException('unknown pid type')