code: def fetch(self, filter=None, order_by=None, group_by=[], page=None, page_size=None, query_parameters=None, commit=True, async=False, callback=None):
          
  
          request = NURESTRequest(method=HTTP_METHOD_GET, url=self._prepare_url(), params=query_parameters)
  
          self._prepare_headers(request=request, filter=filter, order_by=order_by, group_by=group_by, page=page, page_size=page_size)
  
          if async:
              return self.parent_object.send_request(request=request, async=async, local_callback=self._did_fetch, remote_callback=callback, user_info={'commit': commit})
  
          connection = self.parent_object.send_request(request=request, user_info={'commit': commit})
          return self._did_fetch(connection=connection)
docs: Fetch objects according to given filter and page.
  
              Note:
                  This method fetches all managed class objects and store them
                  in local_name of the served object. which means that the parent
                  object will hold them in a list. You can prevent this behavior
                  by setting commit to False. In that case, the fetched children
                  won't be added in the parent object cache.
  
              Args:
                  filter (string): string that represents a predicate filter
                  order_by (string): string that represents an order by clause
                  group_by (string): list of names for grouping
                  page (int): number of the page to load
                  page_size (int): number of results per page
                  commit (bool): boolean to update current object
                  callback (function): Callback that should be called in case of a async request
  
              Returns:
                  tuple: Returns a tuple of information (fetcher, served object, fetched objects, connection)
  
              Example:
                  >>> entity.children.fetch()
                  (<NUChildrenFetcher at aaaa>, <NUEntity at bbbb>, [<NUChildren at ccc>, <NUChildren at ddd>], <NURESTConnection at zzz>)