> For clean Markdown content of this page, append .md to this URL. For the complete documentation index, see https://buildwithfern.com/learn/llms.txt. ## 5.27.1 **`(fix):`** Accept a plain string for the root client's `token` parameter when OAuth client credentials are configured with a token override. The constructor overload, implementation signature, and docstring previously typed `token` as `typing.Callable[[], str]` only, even though the client wrapper accepts `typing.Union[str, typing.Callable[[], str]]` at runtime and the generated example passes a string literal, so type checkers rejected the documented usage.