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: service.go
    path of file: ./repos/teller/vendor/google.golang.org/grpc/credentials/alts/internal/handshaker/service
    
    the code of the file until where you have to start completion: /*
 *
 * Copyright 2018 gRPC authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this f
    
func Dial(hsAddress string) (*grpc.ClientConn, error) {
	mu.Lock()
	defer mu.Unlock()

	hsConn, ok := hsConnMap[hsAddress]
	if !ok {
		// Create a new connection to the handshaker service. Note that
		// this connection stays open until the application is closed.
		var err error
		hsConn, err = hsDialer(hsAddress, grpc.WithInsecure())
		if err != nil {
			return nil, err
		}
		hsConnMap[hsAddress] = hsConn
	}
	return hsConn, nil
}