code: func RunSSHCommand(cmd, user, host string, signer ssh.Signer) (string, string, int, error) {
  	return runSSHCommand(&realSSHDialer{}, cmd, user, host, signer)
  }
docs: // RunSSHCommand returns the stdout, stderr, and exit code from running cmd on
  // host as specific user, along with any SSH-level error.
  // If user=="", it will default (like SSH) to os.Getenv("USER")