code: def test_frequency_double_side_band_class_method_convert():
      """Test the frequency double side band object: test the class method convert."""
      frq_dsb = FrequencyDoubleSideBand(183, 7, 2)
  
      res = frq_dsb.convert(185)
      assert res == 185
  
      res = frq_dsb.convert({"central": 185, "side": 7, "bandwidth": 2})
      assert res == FrequencyDoubleSideBand(185, 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 13 for calling a global function with example usage: test_frequency_double_side_band_class_method_convert() without return types