code: def test_invalid_file(self):
      with pytest.raises(FileNotFoundError):
          KG("foo")
  
      with pytest.raises(FileNotFoundError):
          KG("samples/mutag/")
  
imports: import numpy
  import pytest
  from pyrdf2vec.graphs import KG, Vertex
label_desc: Use image node_id 9 for calling the TestKG obj's underlying member method code with example usage: obj.test_invalid_file() without return types