def skip_internal(app, what, name, obj, skip, options):
    """Skip rendering autodoc when the docstring contains a line with
    only the string `:internal:`.
    """
    docstring = inspect.getdoc(obj) or ""

    if skip or re.search(r"^\s*:internal:\s*$", docstring, re.M) is not None:
        return True
Skip rendering autodoc when the docstring contains a line with
    only the string `:internal:`.