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: idl.go
    path of file: ./repos/evans/idl
    
    the code of the file until where you have to start completion: // Package idl represents an Interface Definition Language (IDL) for gRPC.
// In general, Protocol Buffers is used as the IDL. However, it is possible to use another ID
    
func FullyQualifiedMethodName(fqsn, methodName string) (string, error) {
	if fqsn == "" {
		return "", errors.New("fqsn should not be empty")
	}
	if methodName == "" {
		return "", errors.New("methodName should not be empty")
	}
	return strings.Join([]string{fqsn, methodName}, "."), nil
}