new_contents: import os
  from pathlib import Path
  
  import numpy as np
  from numpy.testing import assert_
  
  ROOT = Path(np.__file__).parents[0]
  FILES = [
      ROOT / "py.typed",
      ROOT / "__init__.pyi",
      ROOT / "char.pyi",
      ROOT / "ctypeslib.pyi",
      ROOT / "emath.pyi",
      ROOT / "rec.pyi",
      ROOT / "version.pyi",
      ROOT / "core" / "__init__.pyi",
      ROOT / "distutils" / "__init__.pyi",
      ROOT / "f2py" / "__init__.pyi",
      ROOT / "fft" / "__init__.pyi",
      ROOT / "lib" / "__init__.pyi",
      ROOT / "linalg" / "__init__.pyi",
      ROOT / "ma" / "__init__.pyi",
      ROOT / "matrixlib" / "__init__.pyi",
      ROOT / "polynomial" / "__init__.pyi",
      ROOT / "random" / "__init__.pyi",
      ROOT / "testing" / "__init__.pyi",
  ]
  
  
  class TestIsFile:
      def test_isfile(self):
          """Test if all ``.pyi`` files are properly installed."""
          for file in FILES:
              assert_(os.path.isfile(file))
  
subject: Validate the existence of `.pyi` stub files