code: def test_data_source_identifier_fetch_loader(source_identifier):
      src_identifier, data_src = source_identifier
      loader = src_identifier.fetch_loader()
      data = loader(data_src)
      assert (
          isinstance(data, np.ndarray)
          or isinstance(data, pd.DataFrame)
          or isinstance(data, type(chunks([])))
      ), "Returned data should be either in numpy array or pandas data frame, instead got {}".format(
          type(data)
      )
  
file_path: AmpliGraph/tests/ampligraph/datasets/test_source_identifier.py
imports: import numpy
  import pytest
  import pandas
  from ampligraph.datasets import load_csv, chunks
  from ampligraph.datasets.source_identifier import DataSourceIdentifier
  import os
label_desc: Use image node_id 7 for calling a global function with example usage: test_data_source_identifier_fetch_loader(source_identifier) without return types