code: function regExpBuilder (find) {
    const regExpRe = /\/(.*)\/(\w*)/
    if (find) {
      if (regExpRe.test(find)) {
        const matches = find.match(regExpRe)
        const pattern = matches[1]
        const flags = matches[2]
        return new RegExp(pattern, flags)
      } else {
        return find
      }
    } else {
      return null
    }
  }
docs: Convert a string like `/something/g` to a RegExp instance.