docs: def concat(regex_list):
      """
      Concat multiple regular expression into one, if the given regular expression is not packed,
      a pair of paren will be add.
  
      >>> reg_1 = r'a|b'
      >>> reg_2 = r'(c|d|e)'
      >>> concat([reg_1, reg2])
      (a|b)(c|d|e)
      """
      output_list = []
  
      for regex in regex_list:
          output_list.append(consolidate(regex))
      return r''.join(output_list)