code: def test_OneMatrix_power():
      o = OneMatrix(3, 3)
      assert o**0 == Identity(3)
      assert o**1 == o
      assert o * o == o**2 == 3 * o
      assert o * o * o == o**3 == 9 * o
  
      o = OneMatrix(n, n)
      assert o * o == o**2 == n * o
      # powsimp necessary as n ** (n - 2) * n does not produce n ** (n - 1)
      assert powsimp(o ** (n - 1) * o) == o**n == n ** (n - 1) * o
  
imports: from sympy.functions.elementary.miscellaneous import sqrt
  from sympy.simplify.powsimp import powsimp
  from sympy.testing.pytest import raises
  from sympy.core.expr import unchanged
  from sympy.core import symbols, S
  from sympy.matrices import Identity, MatrixSymbol, ImmutableMatrix, ZeroMatrix, OneMatrix, Matrix
  from sympy.matrices.exceptions import NonSquareMatrixError
  from sympy.matrices.expressions import MatPow, MatAdd, MatMul
  from sympy.matrices.expressions.inverse import Inverse
  from sympy.matrices.expressions.matexpr import MatrixElement
label_desc: Use image node_id 12 for calling a global function with example usage: test_OneMatrix_power() without return types