code: def test_parallel_axis_theorem():
      # This tests the parallel axis theorem matrix by comparing to test
      # matrices.
  
      # First case, 1 in all directions.
      mat1 = Matrix(((2, -1, -1), (-1, 2, -1), (-1, -1, 2)))
      assert pat_matrix(1, 1, 1, 1) == mat1
      assert pat_matrix(2, 1, 1, 1) == 2 * mat1
  
      # Second case, 1 in x, 0 in all others
      mat2 = Matrix(((0, 0, 0), (0, 1, 0), (0, 0, 1)))
      assert pat_matrix(1, 1, 0, 0) == mat2
      assert pat_matrix(2, 1, 0, 0) == 2 * mat2
  
      # Third case, 1 in y, 0 in all others
      mat3 = Matrix(((1, 0, 0), (0, 0, 0), (0, 0, 1)))
      assert pat_matrix(1, 0, 1, 0) == mat3
      assert pat_matrix(2, 0, 1, 0) == 2 * mat3
  
      # Fourth case, 1 in z, 0 in all others
      mat4 = Matrix(((1, 0, 0), (0, 1, 0), (0, 0, 0)))
      assert pat_matrix(1, 0, 0, 1) == mat4
      assert pat_matrix(2, 0, 0, 1) == 2 * mat4
  
file_path: sympy/sympy/physics/tests/test_physics_matrices.py
imports: from sympy.physics.matrices import msigma, mgamma, minkowski_tensor, pat_matrix, mdft
  from sympy.core.numbers import I, Rational
  from sympy.core.singleton import S
  from sympy.functions.elementary.miscellaneous import sqrt
  from sympy.matrices.dense import Matrix, eye, zeros
  from sympy.testing.pytest import warns_deprecated_sympy
label_desc: Use image node_id 1 for calling a global function with example usage: test_parallel_axis_theorem() without return types