def METHOD_NAME(self, field_path):
    field = self
    nested = []
    parts = field_path.split(".")
    for i, step in enumerate(parts):
        try:
            field = field[step]
        except KeyError:
            return (), None
        if isinstance(field, Nested):
            nested.append(".".join(parts[: i + 1]))
    return nested, field