code: def test_umap_unavailable():
      """
      Assert an appropriate exception is raised when UMAP is not installed
      """
      from yellowbrick.text.umap_vis import UMAP
  
      assert UMAP is None
  
      with pytest.raises(
          YellowbrickValueError,
          match="umap package doesn't seem to be installed",
      ):
          UMAPVisualizer()
  
imports: import sys
  import pytest
  import warnings
  from unittest import mock
  from tests.base import VisualTestCase
  from yellowbrick.text.umap_vis import *
  from yellowbrick.datasets import load_hobbies
  from yellowbrick.exceptions import YellowbrickValueError
  from sklearn.datasets import make_classification
  from sklearn.feature_extraction.text import TfidfVectorizer
label_desc: Use image node_id 1 for calling a global function with example usage: test_umap_unavailable() without return types