This is a bugfix release that fixes the ability to negate membership expressions if !(1 in [2,3,4]) {...}
through #240.
This bug has affected ABS since membership testing was introduced. Workaround for previous versions:
if 1 in [] {
} else {
// execute your code here
}
While from 1.4.1 you can:
if !(1 in []) {
// execute your code
}