Type Alias ContextWatcherCallback 

pub type ContextWatcherCallback = for<'a, 'py> fn(Python<'py>, ContextEvent<'a, 'py>) -> PyResult<()>;

Available on Py_3_14 and neither GraalPy nor Py_LIMITED_API nor PyPy nor RustPython and non-Py_GIL_DISABLED only.

The safe callback signature accepted by context watcher trampolines.