docstr: Test provided cache doesn't have a 'matrices' keyword.
docstr_tok: ["Test","provided","cache","does","n't","have","a","'matrices","'","keyword","."]
code: def test_matrices_not_in_cache(self, mat, op):
      """Test provided cache doesn't have a 'matrices' keyword."""
      assert op.label(cache={}) == "U"
  
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 2 for calling the TestUnitaryLabels obj's underlying member method code with example usage: obj.test_matrices_not_in_cache(mat, op) without return types