code: function re (opts) {
    opts = opts || {}
  
    return new RegExp(
      format('\\b(?:%s)\\b', regexp.versioned.source + (opts.nil ? '|' + regexp.nil.source : '')),
      'i' + (opts.flags || '')
    )
  }
docs: RegExp for finding an RFC4122 compliant UUID in a string.
  
  @param {Object} opts
  Options object.
  
  @param {String} [opts.flags]
  Additional RegExp flags ('i' is always set).
  
  @param {Boolean} [opts.nil]
  Whether to include the nil/empty UUID pattern.
  
  @return {RegExp}
  RegExp for finding an RFC4122 compliant UUID in a string.