code: def test_correct_parameters_multi_channels(self, boundaries):
      self.assertIsInstance(
          SignalRandScale(boundaries), SignalRandScale
      )
      sig = np.load(TEST_SIGNAL)
      scaled = SignalRandScale(boundaries)
      scaledsignal = scaled(sig)
      self.assertEqual(scaledsignal.shape[1], sig.shape[1])
  
file_path: MONAI/tests/test_signal_rand_scale.py
imports: from __future__ import annotations
  import os
  import unittest
  import numpy
  from parameterized import parameterized
  from monai.transforms import SignalRandScale
  from monai.utils.type_conversion import convert_to_tensor
label_desc: Use image node_id 1 for calling the TestSignalRandScaleNumpy obj's underlying member method code with example usage: obj.test_correct_parameters_multi_channels(boundaries) without return types