code: def find_existing_configs(self, default):
          '''
          Find configuration files on the system.
          :return:
          '''
          configs = []
          for cfg in [default, self._config_filename_, 'minion', 'proxy', 'cloud', 'spm']:
              if not cfg:
                  continue
              config_path = self.get_config_file_path(cfg)
              if os.path.exists(config_path):
                  configs.append(cfg)
  
          if default and default not in configs:
              raise SystemExit('Unknown configuration unit: {}'.format(default))
  
          return configf find_existing_configs(self, default):
          '''
          Find configuration files on the system.
          :return:
          '''
          configs = []
          for cfg in [default, self._config_filename_, 'minion', 'proxy', 'cloud', 'spm']:
              if not cfg:
                  continue
              config_path = self.get_config_file_path(cfg)
              if os.path.exists(config_path):
                  configs.append(cfg)
  
          if default and default not in configs:
              raise SystemExit('Unknown configuration unit: {}'.format(default))
  
          return configs
docs: Find configuration files on the system.
          :return: