// MustFromHex is a convenience-constructor to create an Int from
// a hexadecimal string.
// Returns a new Int and panics if any error occurred.
func MustFromHex(hex string) *Int 

// MustFromDecimal is a convenience-constructor to create an Int from a
// decimal (base 10) string.
// Returns a new Int and panics if any error occurred.
func MustFromDecimal(decimal string) *Int