code: def test_frequency_double_side_band_channel_distances():
      """Test the frequency double side band object: get the distance between two bands."""
      frq_dsb = FrequencyDoubleSideBand(183, 7, 2)
      mydist = frq_dsb.distance(175.5)
      assert mydist == 0.5
  
      mydist = frq_dsb.distance(190.5)
      assert mydist == 0.5
  
      np.testing.assert_almost_equal(frq_dsb.distance(175.6), 0.4)
      np.testing.assert_almost_equal(frq_dsb.distance(190.1), 0.1)
  
      mydist = frq_dsb.distance(185)
      assert mydist == np.inf
  
      mydist = frq_dsb.distance((183, 7.0, 2))
      assert mydist == 0
  
      mydist = frq_dsb.distance((183, 7.0, 1))
      assert mydist == 0
  
      mydist = frq_dsb.distance(FrequencyDoubleSideBand(183, 7.0, 2))
      assert mydist == 0
  
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 16 for calling a global function with example usage: test_frequency_double_side_band_channel_distances() without return types