ARITH_ASS
token = ARITH_ASS;
ARITH_ASS + ARITH_ASS_GAP != ARITH_EQ
if (op != ARITH_ASS && (op < ARITH_ASS_MIN || op >= ARITH_ASS_MAX))
if (op != ARITH_ASS)
ARITH_ASS + ARITH_ASS_GAP != ARITH_EQ