func (v Vec) String() string {
	return fmt.Sprintf("(%.4g,%.4g)", v.X, v.Y)
}
func (v Vec) String() string {
	return fmt.Sprintf("(%.4g,%.4g)", v.X, v.Y)
}
func ( v Vec ) String ( ) string { return fmt . Sprintf ( " " , v . X , v . Y ) }
// String returns a string representation of v like "(3,4)".
String returns a string representation of v like ( 3 4 ) .