docs: def hex_digit(coord, digit=1):
      """
      Returns either the first or second digit of the hexadecimal representation of the given coordinate.
      :param coord: hexadecimal coordinate, int
      :param digit: 1 or 2, meaning either the first or second digit of the hexadecimal
      :return: int, either the first or second digit
      """
      if digit not in [1,2]:
          raise ValueError('hex_digit can only get the first or second digit of a hex number, was passed digit={}'.format(
              digit
          ))
      return int(hex(coord)[1+digit], 16)