code: def set_(dic, path, val, seps=PATH_SEPS):
      
      merge(dic, mk_nested_dic(path, val, seps), ac_merge=MS_DICTS)
docs: setter for nested dicts.
  
      :param dic: a dict[-like] object support recursive merge operations
      :param path: Path expression to point object wanted
      :param seps: Separator char candidates
  
      >>> d = dict(a=1, b=dict(c=2, ))
      >>> set_(d, 'a.b.d', 3)
      >>> d['a']['b']['d']
      3