m.doinit()
	x.doinit()
	y.doinit()
	z.doinit()
	if m == nil {
		C.mpz_pow_ui(&z.i[0], &x.i[0], C.mpz_get_ui(&y.i[0]))
	} else {
		C.mpz_powm(&z.i[0], &x.i[0], &y.i[0], &m.i[0])
	}
	return z
}

func (z *Int) Int64() int64 {
	if !z.init {
		return 0
	}
	return int64(C.mpz_get_si(&z.i[0]))
}

// Neg sets z = -x and returns z.
func (z *Int) Neg(x *Int) *Int {
	x.doinit()