class_docstr: A SQLAlchemy :class:`~sqlalchemy.orm.Session` class that chooses what engine to
  use based on the bind key associated with the metadata associated with the thing
  being queried.
  
  To customize ``db.session``, subclass this and pass it as the ``class_`` key in the
  ``session_options`` to :class:`.SQLAlchemy`.
  
  .. versionchanged:: 3.0
      Renamed from ``SignallingSession``.
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code: def __init__(self, db: SQLAlchemy, **kwargs: t.Any) -> None:
      super().__init__(**kwargs)
      self._db = db
      self._model_changes: dict[object, tuple[t.Any, str]] = {}
  
file_path: flask-sqlalchemy/src/flask_sqlalchemy/session.py
imports: from __future__ import annotations
  import typing
  import sqlalchemy
  import sqlalchemy.exc
  import sqlalchemy.orm
  from flask.globals import app_ctx
label_desc: Use image node_id 1 to create a new Session object from inherited base classes: sa_orm with example: obj = Session(db)