new_contents: class Serializer(object):
  
      def serialize(self, data):
          if isinstance(data, list):
              return '[' + ','.join([self.serialize(elem) for elem in data]) + ']'
          if isinstance(data, dict):
              return '{' + ','.join([self.serialize(k) + ':' + self.serialize(v) for k, v in data.iteritems()]) + '}'
          if isinstance(data, (int, float)):
              return str(data)
          if isinstance(data, str):
              return '"' + data + '"'
  
  
  class Parser(object):
  
      def parse(self, data):
          pass
  
subject: add json serialize