code: func IsContextNotFound(err error) bool {
  	if err == nil {
  		return false
  	}
  	if _, ok := err.(*errContextNotFound); ok || err == ErrNoContext {
  		return true
  	}
  	return strings.Contains(err.Error(), "context was not found for specified context")
  }
docs: // IsContextNotFound returns a boolean indicating whether the error is known to
  // report that a context was not found