def get_fn_schema_from_fn_name(
        self, fn_name: str, spec_functions: Optional[List[SPEC_FUNCTION_TYPE]] = None
    ) -> Optional[Type[BaseModel]]:
        """
        NOTE: This function is deprecated and kept only for backwards compatibility.

        Return map from function name.

        Return type is Optional, meaning that the schema can be None.
        In this case, it's up to the downstream tool implementation to infer the schema.

        """
        return None

        NOTE: This function is deprecated and kept only for backwards compatibility.

        Return map from function name.

        Return type is Optional, meaning that the schema can be None.
        In this case, it's up to the downstream tool implementation to infer the schema.

        
llama-index-core/llama_index/core/tools/tool_spec/base.py