docstr: If something exists in the matrix list, but parameter is not in the list, then parameter
  added to list and label given number of its position.
docstr_tok: ["If","something","exists","in","the","matrix","list",",","but","parameter","is","not","in","the","list",",","then","parameter","added","to","list","and","label","given","number","of","its","position","."]
code: def test_something_in_cache_list(self, mat, op):
      """If something exists in the matrix list, but parameter is not in the list, then parameter
      added to list and label given number of its position."""
      cache = {"matrices": [TSWAP]}
      assert op.label(cache=cache) == "U(M1)"
  
      assert len(cache["matrices"]) == 2
      assert qml.math.allclose(cache["matrices"][1], mat)
  
imports: import pytest
  import numpy
  from scipy.stats import unitary_group
  from gate_data import TSWAP
  import pennylane
  from pennylane.wires import Wires
  from pennylane.operation import DecompositionUndefinedError
label_desc: Use image node_id 5 for calling the TestUnitaryLabels obj's underlying member method code with example usage: obj.test_something_in_cache_list(mat, op) without return types