code: def update_settings(self, d, role, path='roles/{role}/settings.yaml'):
          
          try:
              import ruamel.yaml
              load_func = ruamel.yaml.round_trip_load
              dump_func = ruamel.yaml.round_trip_dump
          except ImportError:
              print('Warning: ruamel.yaml not available, reverting to yaml package, possible lost of formatting may occur.')
              import yaml
              load_func = yaml.load
              dump_func = yaml.dump
          settings_fn = path.format(role=role)
          data = load_func(open(settings_fn))
          data.update(d)
          settings_str = dump_func(data)
          open(settings_fn, 'w').write(settings_str)
docs: Writes a key/value pair to a settings file.