code: def test_parent_some_missing(self, values_es, true_values_lti):
      # test dataframe with time index and not all instances have children
      if values_es.dataframe_type != Library.PANDAS:
          pytest.xfail("fails with Dask, tests needs to be reworked")
      values = values_es["values"]
  
      # add extra value instance with no children
      row_values = {
          "value": [21.0],
          "value_time": [pd.Timestamp("2011-04-10 11:10:02")],
      }
      # make sure index doesn't have same name as column to suppress pandas warning
      row = pd.DataFrame(row_values, index=pd.Index([21]))
      df = pd.concat([values, row])
      df = df.sort_values(by="value")
      df.index.name = None
  
      values_es.replace_dataframe(dataframe_name="values", df=df)
      values_es.add_last_time_indexes()
      # lti value should default to instance's time index
      true_values_lti[10] = pd.Timestamp("2011-04-10 11:10:02")
      true_values_lti[11] = pd.Timestamp("2011-04-10 11:10:03")
  
      values = values_es["values"]
      lti_name = values.ww.metadata.get("last_time_index")
      assert len(values[lti_name]) == 11
      sorted_lti = values[lti_name].sort_index()
      for v1, v2 in zip(sorted_lti, true_values_lti):
          assert (pd.isnull(v1) and pd.isnull(v2)) or v1 == v2
  
imports: from datetime import datetime
  import pandas
  import pytest
  from woodwork.logical_types import Categorical, Datetime, Integer
  from featuretools.entityset.entityset import LTI_COLUMN_NAME
  from featuretools.tests.testing_utils import to_pandas
  from featuretools.utils.gen_utils import Library, import_or_none
label_desc: Use image node_id 4 for calling the TestLastTimeIndex obj's underlying member method code with example usage: obj.test_parent_some_missing(values_es, true_values_lti) without return types