code: def test_Pauli():
      # this and the following test are testing both Pauli and Dirac matrices
      # and also that the general Matrix class works correctly in a real world
      # situation
      sigma1 = msigma(1)
      sigma2 = msigma(2)
      sigma3 = msigma(3)
  
      assert sigma1 == sigma1
      assert sigma1 != sigma2
  
      # sigma*I -> I*sigma    (see #354)
      assert sigma1 * sigma2 == sigma3 * I
      assert sigma3 * sigma1 == sigma2 * I
      assert sigma2 * sigma3 == sigma1 * I
  
      assert sigma1 * sigma1 == eye(2)
      assert sigma2 * sigma2 == eye(2)
      assert sigma3 * sigma3 == eye(2)
  
      assert sigma1 * 2 * sigma1 == 2 * eye(2)
      assert sigma1 * sigma3 * sigma1 == -sigma3
  
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 2 for calling a global function with example usage: test_Pauli() without return types