code: def _serialize_dict(cls, dict_):
          
  
          obj_serialized = {}
  
          for key in dict_.keys():
              item_serialized = cls.serialize(dict_[key])
  
              if item_serialized is not None:
                  key = key.rstrip(cls._SUFFIX_KEY_OVERLAPPING)
                  key = key.lstrip(cls._PREFIX_KEY_PROTECTED)
                  obj_serialized[key] = item_serialized
  
          return obj_serialized
docs: :type dict_ dict
  
          :rtype: dict