code: def _expand_tuple(path_cfg, alias_dict, overriding_kargs):
      
  
      # e.g.,
      # path_cfg = ('ev : {low} <= ev.var[0] < {high}', {'low': 10, 'high': 200})
      # overriding_kargs = {'alias': 'var_cut', 'name': 'var_cut25', 'low': 25}
  
      new_path_cfg = path_cfg[0]
      # e.g., 'ev : {low} <= ev.var[0] < {high}'
  
      new_overriding_kargs = path_cfg[1].copy()
      # e.g., {'low': 10, 'high': 200}
  
      new_overriding_kargs.update(overriding_kargs)
      # e.g., {'low': 25, 'high': 200, 'alias': 'var_cut', 'name': 'var_cut25'}
  
      return expand_path_cfg(
          new_path_cfg,
          overriding_kargs=new_overriding_kargs,
          alias_dict=alias_dict
      )
docs: expand a path config given as a tuple