code: def get_work_items(self, ids, project=None, fields=None, as_of=None, expand=None, error_policy=None):
          
          route_values = {}
          if project is not None:
              route_values['project'] = self._serialize.url('project', project, 'str')
          query_parameters = {}
          if ids is not None:
              ids = ",".join(map(str, ids))
              query_parameters['ids'] = self._serialize.query('ids', ids, 'str')
          if fields is not None:
              fields = ",".join(fields)
              query_parameters['fields'] = self._serialize.query('fields', fields, 'str')
          if as_of is not None:
              query_parameters['asOf'] = self._serialize.query('as_of', as_of, 'iso-8601')
          if expand is not None:
              query_parameters['$expand'] = self._serialize.query('expand', expand, 'str')
          if error_policy is not None:
              query_parameters['errorPolicy'] = self._serialize.query('error_policy', error_policy, 'str')
          response = self._send(http_method='GET',
                                location_id='72c7ddf8-2cdc-4f60-90cd-ab71c14a399b',
                                version='5.1-preview.3',
                                route_values=route_values,
                                query_parameters=query_parameters)
          return self._deserialize('[WorkItem]', self._unwrap_collection(response))
docs: GetWorkItems.
          [Preview API] Returns a list of work items (Maximum 200)
          :param [int] ids: The comma-separated list of requested work item ids. (Maximum 200 ids allowed).
          :param str project: Project ID or project name
          :param [str] fields: Comma-separated list of requested fields
          :param datetime as_of: AsOf UTC date time string
          :param str expand: The expand parameters for work item attributes. Possible options are { None, Relations, Fields, Links, All }.
          :param str error_policy: The flag to control error policy in a bulk get work items request. Possible options are {Fail, Omit}.
          :rtype: [WorkItem]