code: func Wrap(message string, err error) error {
  	return xerrors.Errorf("%v: %w", message, err)
  }
docs: // Wrap is a simple wrapper around Errorf that is doing error wrapping. You can read how that works in
  // https://godoc.org/golang.org/x/xerrors#Errorf but its API is very implicit which is a reason for this wrapper.
  // There is also a discussion (https://github.com/golang/go/issues/29934) where many comments make arguments for such
  // wrapper so hopefully it will be added in the standard lib later.