code: def make_null_event_date_events(all_sids, timestamp):
      """
      Make an event with a null event_date for all sids.
  
      Used to test that EventsLoaders filter out null events.
      """
      return pd.DataFrame(
          {
              "sid": all_sids,
              "timestamp": timestamp,
              "event_date": pd.Timestamp("NaT"),
              "float": -9999.0,
              "int": -9999,
              "datetime": pd.Timestamp("1980"),
              "string": "should be ignored",
          }
      )
  
imports: from datetime import time
  import itertools
  from itertools import product
  import blaze
  from nose_parameterized import parameterized
  import numpy
  import pandas
  from catalyst.pipeline import Pipeline, SimplePipelineEngine
  from catalyst.pipeline.common import EVENT_DATE_FIELD_NAME, TS_FIELD_NAME, SID_FIELD_NAME
  from catalyst.pipeline.data import DataSet, Column
  from catalyst.pipeline.loaders.events import EventsLoader
  from catalyst.pipeline.loaders.blaze.events import BlazeEventsLoader
  from catalyst.pipeline.loaders.utils import next_event_indexer, normalize_timestamp_to_query_time, previous_event_indexer
  from catalyst.testing import check_arrays, CatalystTestCase
  from catalyst.testing.fixtures import WithAssetFinder, WithTradingSessions
  from catalyst.testing.predicates import assert_equal
  from catalyst.utils.numpy_utils import categorical_dtype, datetime64ns_dtype, float64_dtype, int64_dtype
label_desc: Use image node_id 2 for calling a global function with example usage: make_null_event_date_events(all_sids, timestamp) and returns: pd