class_docstr: A map that creates new keys for missing key access.
  
  Produces an incrementing sequence given a series of unique keys.
  
  This is similar to the compiler prefix_anon_map class although simpler.
  
  Inlines the approach taken by :class:`sqlalchemy.util.PopulateDict` which
  is otherwise usually used for this type of operation.
code: def get_anon(self, object_: Any) -> Tuple[str, bool]:
      idself = id(object_)
      if idself in self:
          s_val = self[idself]
          assert s_val is not True
          return s_val, True
      else:
          # inline of __missing__
          self[idself] = id_ = str(self._index)
          self._index += 1
  
          return id_, False
  
file_path: sqlalchemy/lib/sqlalchemy/sql/_py_util.py
imports: from __future__ import annotations
  import typing
  from typing import Any
  from typing import Dict
  from typing import Tuple
  from typing import Union
  from ..util.typing import Literal
label_desc: Use image node_id 1 for calling the cache_anon_map obj's underlying member method code with example usage: obj.get_anon(object_) and returns: s_val,  True, id_,  False