# File lib/active_support/json/backends/okjson.rb, line 366
    def hexdec4(s)
      if s.length != 4
        raise Error, 'short'
      end
      (nibble(s[0])<<12) | (nibble(s[1])<<8) | (nibble(s[2])<<4) | nibble(s[3])
    end