code: def test_frequency_double_side_band_channel_equality():
      """Test the frequency double side band object: check if two bands are 'equal'."""
      frq_dsb = FrequencyDoubleSideBand(183, 7, 2)
      assert frq_dsb is not None
      assert 183 != frq_dsb
      assert 190 == frq_dsb
      assert 176 == frq_dsb
      assert 175.5 == frq_dsb
  
      assert frq_dsb != FrequencyDoubleSideBand(183, 6.5, 3)
  
      frq_dsb = None
      assert FrequencyDoubleSideBand(183, 7, 2) != frq_dsb
  
      assert frq_dsb < FrequencyDoubleSideBand(183, 7, 2)
  
      assert FrequencyDoubleSideBand(
          182, 7, 2
      ) < FrequencyDoubleSideBand(183, 7, 2)
      assert FrequencyDoubleSideBand(
          184, 7, 2
      ) > FrequencyDoubleSideBand(183, 7, 2)
  
imports: import unittest
  from datetime import datetime
  import numpy
  import pytest
  from satpy.dataset.dataid import DataID, DataQuery, ModifierTuple, WavelengthRange, minimal_default_keys_config
  from satpy.readers.pmw_channels_definitions import FrequencyDoubleSideBand, FrequencyQuadrupleSideBand, FrequencyRange
  from satpy.tests.utils import make_cid, make_dataid, make_dsq
label_desc: Use image node_id 15 for calling a global function with example usage: test_frequency_double_side_band_channel_equality() without return types