code: def format_hexadecimal_field(spec, prec, number, locale):
      
      if number < 0:
          # Take two's complement.
          number &= (1 << (8 * int(math.log(-number, 1 << 8) + 1))) - 1
      format_ = u'0%d%s' % (int(prec or 0), spec)
      return format(number, format_)
docs: Formats a hexadeciaml field.