Web サービス呼び出しのタイムアウト エラーを具体的に検出するにはどうすればよいですか?

// If the deadline is exceeded a call to Read or Write or to other
// I/O methods will return an error that wraps os.ErrDeadlineExceeded.
// This can be tested using errors.Is(err, os.ErrDeadlineExceeded).
// The error's Timeout method will return true, but note that there
// are other possible errors for which the Timeout method will
// return true even if the deadline has not been exceeded.

if errors.Is(err, os.ErrDeadlineExceeded) {
  // Handle timeout error
}

if err, ok := err.(net.Error); ok && err.Timeout() {
  // Handle timeout error
}