code: def queryFilter(self, function=None):
          
          if function is not None:
              self.__query_filter = function
              return function
  
          def wrapper(func):
              self.__query_filter = func
              return func
          return wrapper
docs: Defines a decorator that can be used to filter
          queries.  It will assume the function being associated
          with the decorator will take a query as an input and
          return a modified query to use.
  
          :usage
  
              class MyModel(orb.Model):
                  objects = orb.ReverseLookup('Object')
  
                  @classmethod
                  @objects.queryFilter()
                  def objectsFilter(cls, query, **context):
                      return orb.Query()
  
          :param function: <callable>
  
          :return: <wrapper>