old: opcode = head[0] & 0b1111 fin = head[0] >> 7 & 1 is_masked = head[1] >> 7 & 1 modified: opcode = self.bytetonum(head[0]) & 0b1111 fin = self.bytetonum(head[0]) >> 7 & 1 is_masked = self.bytetonum(head[1]) >> 7 & 1