OK: .456 = .456
OK: 123. = 123.
OK: 4 2 + = 6
OK: 123 / is invalid, got no result
OK: 24 abs = 24
OK: 1 24 abs + sqrt = 5
OK: 12 34 is invalid, got no result
OK: 123 34 * chs = -4182
OK: 4 2 - = 2
OK: 34 2 / 2 ^ = 289
OK: 24 4 + chs sqr = 784
OK: 123.456 + is invalid, got no result
OK: 123 chs 34 * = -4182
OK: fail is invalid, got no result
OK: 24 chs abs = 24
OK: 25 abs sqrt = 5
OK: 12 34+ is invalid, got no result
OK: 12 34 + + is invalid, got no result
OK: 123 chs chs chs = -123
OK: 1 24abs+sqrt is invalid, got no result
OK: 12 34 + 56 + = 102
OK: 123 chs = -123
OK: 24 = 24
OK: 1 fail is invalid, got no result
OK: 12 34 56 + + = 102
OK: 4 2 ^ = 16
OK: 123 chs chs chs chs = 123
OK: 3 34 2 / 2 ^ * = 867
OK: 25 chs abs sqrt = 5
OK: 123.456 = 123.456
OK:  123  = 123
OK: 123 chs chs = 123
OK: 24 chs = -24
OK: 123 = 123
OK: 24abs is invalid, got no result
OK: 4 2 / = 2
OK: 24abssqrt is invalid, got no result
OK: 4 2 * = 8