proc `^`*(f: proc(x: untyped): untyped, power: int): proc(x: untyped): untyped =
    ## "Exponentiation" of a function
    ## (f^n)(x) := f(f(f( ... n times ... f(f(f(x))) ... )))
    return proc(x: untyped): untyped =
        result = x
        for _ in 1 .. power:
            result = f(result)