You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: uuid.go
    path of file: ./repos/tank/code/tool/uuid
    
    the code of the file until where you have to start completion: // This package provides immutable UUID structs and the functions
// NewV3, NewV4, NewV5 and Parse() for generating versions 3, 4
// and 5 UUIDs
    
func (u *UUID) Variant() byte {
	if u[8]&ReservedNCS == ReservedNCS {
		return ReservedNCS
	} else if u[8]&ReservedRFC4122 == ReservedRFC4122 {
		return ReservedRFC4122
	} else if u[8]&ReservedMicrosoft == ReservedMicrosoft {
		return ReservedMicrosoft
	}
	return ReservedFuture
}