code: def test_tractogram_file():
      with pytest.raises(NotImplementedError):
          TractogramFile.is_correct_format("")
      with pytest.raises(NotImplementedError):
          TractogramFile.load("")
  
      # Testing calling the 'save' method of `TractogramFile` object.
      class DummyTractogramFile(TractogramFile):
          @classmethod
          def is_correct_format(cls, fileobj):
              return False
  
          @classmethod
          def load(cls, fileobj, lazy_load=True):
              return None
  
          @classmethod
          def save(self, fileobj):
              pass
  
      with pytest.raises(NotImplementedError):
          super(
              DummyTractogramFile, DummyTractogramFile(Tractogram)
          ).save("")
  
imports: import pytest
  from ..tractogram import Tractogram
  from ..tractogram_file import TractogramFile
label_desc: Use image node_id 2 for calling a global function with example usage: test_tractogram_file() and returns: False, None