original.name="Coercion_Valid_10"
======
>>> main.whiley
type pos is (int x) where x >= 0
type neg is (int x) where x < 0

function f(pos x) -> (pos[]|neg[] r):
    return [x]

function g(neg x) -> (pos[]|neg[] r):
    return [x]

public export method test():
    //
    assume f(1) == [1]
    //
    assume g(-1) == [-1]    


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