code: def df_schema():
      return DataFrame(
          {
              "A": [1, 2, 3, 4],
              "B": ["a", "b", "c", "c"],
              "C": pd.date_range("2016-01-01", freq="d", periods=4),
              "D": pd.timedelta_range("1h", periods=4, freq="min"),
          },
          index=pd.Index(range(4), name="idx"),
      )
  
imports: from collections import OrderedDict
  from io import StringIO
  import json
  import numpy
  import pytest
  from pandas.core.dtypes.dtypes import CategoricalDtype, DatetimeTZDtype, PeriodDtype
  import pandas
  from pandas import DataFrame
  import pandas._testing
  from pandas.io.json._table_schema import as_json_table_type, build_table_schema, convert_json_field_to_pandas_type, convert_pandas_type_to_json_field, set_default_names
label_desc: Use image node_id 1 for calling a global function with example usage: df_schema() and returns: DataFrame