original.name="Coercion_Valid_11"
======
>>> main.whiley
type pos is (int x) where x >= 0
type neg is (int x) where x < 0

type A1 is ((pos|neg)[] x)

function f(pos[] xs) -> (A1 rs)
ensures xs == rs:
    return (A1) xs

public export method test():
    assert f([0,1,2]) == [0,1,2]
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