original.name="Switch_Valid_1"
======
>>> main.whiley


type nat is (int n) where n >= 0

function f(int x) -> nat:
    switch x:
        case 1:
            return x - 1
        case -1:
            return x + 1
    return 1

public export method test() :
    assume f(2) == 1
    assume f(1) == 0
    assume f(0) == 1
    assume f(-1) == 0
    assume f(-2) == 1

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