code: def update_config(
          self, filename="MAGTUNE_PYMAGICC.CFG", top_level_key="nml_allcfgs", **kwargs
      ):
          
          kwargs = self._format_config(kwargs)
          fname = join(self.run_dir, filename)
  
          if exists(fname):
              conf = f90nml.read(fname)
          else:
              conf = {top_level_key: {}}
  
          conf[top_level_key].update(kwargs)
          f90nml.write(conf, fname, force=True)
  
          return conf
docs: Updates a configuration file for MAGICC
  
          Updates the contents of a fortran namelist in the run directory,
          creating a new namelist if none exists.
  
          Parameters
          ----------
          filename : str
              Name of configuration file to write
  
          top_level_key : str
              Name of namelist to be written in the
              configuration file
  
          kwargs
              Other parameters to pass to the configuration file. No
              validation on the parameters is performed.
  
          Returns
          -------
          dict
              The contents of the namelist which was written to file