class_docstr: Test the utility function _nonzero_coeffs_and_words.
class_docstr_tok: ["Test","the","utility","function","_nonzero_coeffs_and_words","."]
docstr: Test that a single coefficient in any of the coefficients is sufficient
  to keep the Pauli word in the filter.
docstr_tok: ["Test","that","a","single","coefficient","in","any","of","the","coefficients","is","sufficient","to","keep","the","Pauli","word","in","the","filter","."]
code: def test_separate_nonzero(self, num_wires):
      """Test that a single coefficient in any of the coefficients is sufficient
      to keep the Pauli word in the filter."""
      # Create many coefficients, each greater or equal ``1`` at distinct places.
      rng = np.random.default_rng(42)
      coeffs = tuple(
          rng.uniform(
              1, 2, size=(4**num_wires - 1, 4**num_wires - 1)
          )
      )
      new_coeffs, words = _nonzero_coeffs_and_words(coeffs, num_wires)
  
      # The coefficients should not have changed and all words should be returned
      assert all(
          qml.math.allclose(nc, c) for nc, c in zip(new_coeffs, coeffs)
      )
      assert len(words) == 4**num_wires - 1
      # Also check that the order of the words is consistent.
      assert all(
          w == exp
          for w, exp in zip(words, pauli_basis_strings(num_wires))
      )
  
imports: import copy
  import pytest
  import numpy
  import pennylane
  from pennylane import numpy
  from pennylane.ops.qubit.special_unitary import pauli_basis_matrices, pauli_basis_strings
  from pennylane.math import expand_matrix
  from pennylane.gradients.pulse_gradient_odegen import _generate_tapes_and_coeffs, pulse_odegen, _insert_op, _nonzero_coeffs_and_words, _one_parameter_generators, _one_parameter_paulirot_coeffs, _parshift_and_contract
label_desc: Use image node_id 2 for calling the TestNonzeroCoeffsAndWords obj's underlying member method code with example usage: obj.test_separate_nonzero(num_wires) without return types