code: def df_datetime_daily_idx():
      """Create timeseries with Datetime index, daily frequency."""
      return pd.DataFrame(
          data={"y": [1, 1, 1, 1, 1, 1, 1]},
          index=pd.date_range(start="2000-01-01", freq="D", periods=7),
      )
  
imports: import numpy
  import pandas
  import pytest
  from pandas.testing import assert_frame_equal
  from sktime.datasets import load_airline, load_longley, load_PBS_dataset
  from sktime.split import temporal_train_test_split
  from sktime.tests.test_switch import run_test_for_class
  from sktime.transformations.series.date import DateTimeFeatures
  from sktime.utils._testing.hierarchical import _make_hierarchical
label_desc: Use image node_id 22 for calling a global function with example usage: df_datetime_daily_idx() and returns: pd