old_contents: import pytest
  from quimb.utils import (
      raise_cant_find_library_function,
  )
  
  
  class TestLibraryFinding:
  
      def test_raise_cant_find_library_function(self):
          fn = raise_cant_find_library_function(
              "alibthatisdefinitelynotinstalledasfeasdf")
  
          with pytest.raises(ImportError):
  
              fn()
  
new_contents: import pytest
  from quimb.utils import (
      raise_cant_find_library_function,
      deprecated,
  )
  
  
  class TestLibraryFinding:
  
      def test_raise_cant_find_library_function(self):
          fn = raise_cant_find_library_function(
              "alibthatisdefinitelynotinstalledasfeasdf")
  
          with pytest.raises(ImportError):
              fn()
  
      def test_deprecated(self):
          fn = deprecated(lambda: 2, 'old_two', 'new_two')
  
          with pytest.warns(Warning):
              r = fn()
  
          assert r == 2
  
subject: add deprecated warning test