code: def test_ME_MM():
      assert isinstance(Identity(3) + MM, MatrixExpr)
      assert isinstance(SM + MM, MatAdd)
      assert isinstance(MM + SM, MatAdd)
      assert (Identity(3) + MM)[1, 1] == 6
  
file_path: sympy/sympy/matrices/tests/test_interactions.py
imports: from sympy.core.symbol import symbols
  from sympy.matrices import Matrix, MatrixSymbol, eye, Identity, ImmutableMatrix
  from sympy.matrices.expressions import MatrixExpr, MatAdd
  from sympy.matrices.matrixbase import classof
  from sympy.testing.pytest import raises
label_desc: Use image node_id 2 for calling a global function with example usage: test_ME_MM() without return types