js.compile.ignore=true
=====
>>> main.whiley
public export method test():
int[] xs = [1,2,3]
int[] ys = xs[1:=4][2:=5]
// check xs unchanged
assert xs[0] == 1
assert xs[1] == 2
assert xs[2] == 3
// check ys changed
assert ys[0] == 1
assert ys[1] == 4
assert ys[2] == 5
// Final check
assert ys == [1,4,5]
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