def METHOD_NAME(code_or_name: int | str | Issue) -> ValidationDecorator:
    """ Decorator to mark a validator method for a Bokeh error condition
    Args:
        code_or_name (int, str or Issue) : a code from ``bokeh.validation.errors`` or a string label for a custom check
    Returns:
        callable : decorator for Bokeh model methods
    The function that is decorated should have a name that starts with
    ``_check``, and return a string message in case a bad condition is
    detected, and ``None`` if no bad condition is detected.
    Examples:
    The first example uses a numeric code for a standard warning provided in
    ``bokeh.validation.warnings``. This usage is primarily of interest to Bokeh
    core developers.
    .. code-block:: python
        from bokeh.validation.warnings import MISSING_RENDERERS
        @warning(MISSING_RENDERERS)
        def _check_no_glyph_renderers(self):
            if bad_condition: return "message"
    The second example shows how a custom warning check can be implemented by
    passing an arbitrary string label to the decorator. This usage is primarily
    of interest to anyone extending Bokeh with their own custom models.
    .. code-block:: python
        @warning("MY_CUSTOM_WARNING")
        def _check_my_custom_warning(self):
            if bad_condition: return "message"
    """
    return _validator(code_or_name, "warning")