func go/token.Lookup

3 uses

	go/token (current package)
		token.go#L297: func Lookup(ident string) Token {

	go/scanner
		scanner.go#L843: 			tok = token.Lookup(lit)

	google.golang.org/protobuf/internal/strs
		strings.go#L84: 	if token.Lookup(s).IsKeyword() || !unicode.IsLetter(r) {