code: def test_constant(self):
      x = th.ones(2048)
      for zeros in [4, 10]:
          for freq in [0.01, 0.1]:
              y_low = lowpass_filter(x, freq, zeros=zeros)
              self.assertLessEqual(
                  (y_low - 1).abs().mean(), 1e-6, (zeros, freq)
              )
  
file_path: julius/tests/test_lowpass.py
imports: import random
  import unittest
  import torch
  from julius import LowPassFilter, LowPassFilters, lowpass_filter, resample_frac
  from julius.core import pure_tone
label_desc: Use image node_id 6 for calling the TestLowPassFilters obj's underlying member method code with example usage: obj.test_constant() without return types