docs: def select_regexp_char(char):
      """
      Select correct regex depending the char
      """
      regexp = '{}'.format(char)
  
      if not isinstance(char, str) and not isinstance(char, int):
          regexp = ''
  
      if isinstance(char, str) and not char.isalpha() and not char.isdigit():
          regexp = r"\{}".format(char)
  
      return regexp