def test_in__(self):
        """Function is passed in as an argument.
        """

        def a(i):
            return i + 1

        def foo(f):
            return 0

        sig = int64(int64)

        for decor in [mk_cfunc_func(sig),
                      njit_func,
                      mk_njit_with_sig_func(sig),
                      mk_ctypes_func(sig),
                      mk_wap_func(sig)]:
            for jit_opts in [dict(nopython=True), dict(forceobj=True)]:
                jit_ = jit(**jit_opts)
                with self.subTest(decor=decor.__name__, jit=jit_opts):
                    a_ = decor(a)
                    self.assertEqual(jit_(foo)(a_), foo(a))
Function is passed in as an argument.
        
numba/tests/test_function_type.py