docs: def list_spectrum_descriptions(*args):
      """List all available spectrum descriptions that can be used for peak list simulation.
  
      :param str args: Spectrum name(s), e.g. list_spectrum_descriptions("HNCO", "HNcoCACB"), leave empty to list everything.
      :return: None
      :rtype: :py:obj:`None`
      """
      if args:
          for spectrum_name in args:
              pprint.pprint({spectrum_name: SPECTRUM_DESCRIPTIONS.get(spectrum_name, None)}, width=120)
      else:
          pprint.pprint(SPECTRUM_DESCRIPTIONS, width=120)