function deprecated(text, alt) {
  if (!alt) {
    return text + " (DEPRECATED)";
  }

  return text + " (DEPRECATED, use " + alt + " instead)";
}
Returns the same text but with a deprecation notice.
Useful for options descriptions.

@param {string} text
@param {string} alt (optional) Alternative command to include in the
                deprecation notice.

@returns {string}