code: def test_dask_mg_k_core_invalid_input(dask_client):
      input_data_path = datasets[0]
      chunksize = dcg.get_chunksize(input_data_path)
      ddf = dask_cudf.read_csv(
          input_data_path,
          chunksize=chunksize,
          delimiter=" ",
          names=["src", "dst", "value"],
          dtype=["int32", "int32", "float32"],
      )
  
      dg = cugraph.Graph(directed=True)
      dg.from_dask_cudf_edgelist(
          ddf,
          source="src",
          destination="dst",
          edge_attr="value",
          renumber=True,
          store_transposed=True,
      )
      with pytest.raises(ValueError):
          dcg.k_core(dg)
  
      dg = cugraph.Graph(directed=False)
      dg.from_dask_cudf_edgelist(
          ddf,
          source="src",
          destination="dst",
          edge_attr="value",
          store_transposed=True,
      )
  
      degree_type = "invalid"
      with pytest.raises(ValueError):
          dcg.k_core(dg, degree_type=degree_type)
  
file_path: cugraph/python/cugraph/cugraph/tests/core/test_k_core_mg.py
imports: import gc
  import pytest
  import dask_cudf
  import cugraph
  import cugraph.dask
  from cugraph.testing import utils
  from cudf.testing.testing import assert_frame_equal
  from cugraph.structure.symmetrize import symmetrize_df
  from pylibcugraph.testing import gen_fixture_params_product
label_desc: Use image node_id 6 for calling a global function with example usage: test_dask_mg_k_core_invalid_input(dask_client) without return types