class_docstr: Tests for the frequencies_to_period function
class_docstr_tok: ["Tests","for","the","frequencies_to_period","function"]
docstr: Test with non-equidistant frequencies.
code: def test_nonequidistant_frequencies(self):
      """Test with non-equidistant frequencies."""
      res = frequencies_to_period((1.8, 2.7, 9.0))
      expected = 2 * np.pi / 0.9
      assert res == expected
  
imports: import pytest
  import numpy
  import pennylane
  from pennylane.gradients.general_shift_rules import eigvals_to_frequencies, frequencies_to_period, generate_shift_rule, _get_shift_rule, generate_multi_shift_rule, generate_shifted_tapes, generate_multishifted_tapes, _iterate_shift_rule_with_multipliers
label_desc: Use image node_id 3 for calling the TestFrequenciesToPeriod obj's underlying member method code with example usage: obj.test_nonequidistant_frequencies() without return types