code: def test_frequency_quadruple_side_band_channel_str():
      """Test the frequency quadruple side band object: test the band description."""
      frq_qdsb1 = FrequencyQuadrupleSideBand(57.0, 0.322, 0.05, 0.036)
      frq_qdsb2 = FrequencyQuadrupleSideBand(57000, 322, 50, 36, "MHz")
  
      assert (
          str(frq_qdsb1)
          == "central=57.0 GHz ±0.322 ±0.05 width=0.036 GHz"
      )
      assert str(frq_qdsb2) == "central=57000 MHz ±322 ±50 width=36 MHz"
  
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 9 for calling a global function with example usage: test_frequency_quadruple_side_band_channel_str() without return types