code: def test_dataframe_without_name(es):
      new_es = EntitySet()
  
      new_df = es["sessions"].copy()
  
      assert new_df.ww.schema is None
  
      error = "Cannot add dataframe to EntitySet without a name. Please provide a value for the dataframe_name parameter."
      with pytest.raises(ValueError, match=error):
          new_es.add_dataframe(new_df)
  
imports: from datetime import datetime
  import numpy
  import pandas
  import pytest
  from woodwork.exceptions import TypeConversionError
  from woodwork.logical_types import Boolean, Categorical, Datetime, Double, Integer, NaturalLanguage
  from featuretools.entityset.entityset import LTI_COLUMN_NAME, EntitySet
  from featuretools.tests.testing_utils import to_pandas
  from featuretools.utils.gen_utils import Library, import_or_none, is_instance
label_desc: Use image node_id 27 for calling a global function with example usage: test_dataframe_without_name(es) without return types