Creates a hint with the exc info filled in.

def event_hint_with_exc_info(exc_info=None):
    # type: (ExcInfo) -> Dict[str, Optional[ExcInfo]]
    """Creates a hint with the exc info filled in."""
    if exc_info is None:
        exc_info = sys.exc_info()
    else:
        exc_info = exc_info_from_error(exc_info)
    if exc_info[0] is None:
        exc_info = None
    return {"exc_info": exc_info}