def innermost_base(
        bases: Optional[Sequence[pyschema_utils.Class]] = None,
        among_modules=set(["langchain", "llama_index", "trulens"]),
    ) -> Optional[str]:
        """
        Given a sequence of classes, return the first one which comes from one
        of the `among_modules`. You can use this to determine where ultimately
        the encoded class comes from in terms of langchain, llama_index, or
        trulens even in cases they extend each other's classes. Returns
        None if no module from `among_modules` is named in `bases`.
        """
        if bases is None:
            return None

        for base in bases:
            if "." in base.module.module_name:
                root_module = base.module.module_name.split(".")[0]
            else:
                root_module = base.module.module_name

            if root_module in among_modules:
                return root_module

        return None

        Given a sequence of classes, return the first one which comes from one
        of the `among_modules`. You can use this to determine where ultimately
        the encoded class comes from in terms of langchain, llama_index, or
        trulens even in cases they extend each other's classes. Returns
        None if no module from `among_modules` is named in `bases`.
        
src/core/trulens/core/app.py