langchain/tools/python/tool.py/PythonAstREPLTool/_run
class PythonAstREPLTool:    def _run(
        self,
        query: str,
        run_manager: Optional[CallbackManagerForToolRun] = None,
    ) -> str:
        """Use the tool."""
        try:
            if self.sanitize_input:
                query = sanitize_input(query)
            tree = ast.parse(query)
            module = ast.Module(tree.body[:-1], type_ignores=[])
            exec(ast.unparse(module), self.globals, self.locals)  # type: ignore
            module_end = ast.Module(tree.body[-1:], type_ignores=[])
            module_end_str = ast.unparse(module_end)  # type: ignore
            io_buffer = StringIO()
            try:
                with redirect_stdout(io_buffer):
                    ret = eval(module_end_str, self.globals, self.locals)
                    if ret is None:
                        return io_buffer.getvalue()
                    else:
                        return ret
            except Exception:
                with redirect_stdout(io_buffer):
                    exec(module_end_str, self.globals, self.locals)
                return io_buffer.getvalue()
        except Exception as e:
            return "{}: {}".format(type(e).__name__, str(e))