`selector` is a CSS selector or `'.'`. `filter` must be in the special JointJS filter format: `{ name: <name of the filter>, args: { <arguments>, ... }`. An example is: `{ filter: { name: 'blur', args: { radius: 5 } } }`.
function(selector, filter) {

        var $selected = this.findBySelector(selector);

        // Generate a hash code from the stringified filter definition. This gives us
        // a unique filter ID for different definitions.
        var filterId = filter.name + this.paper.svg.id + joint.util.hashCode(JSON.stringify(filter));

        // If the filter already exists in the document,
        // we're done and we can just use it (reference it using `url()`).
        // If not, create one.
        if (!this.paper.svg.getElementById(filterId)) {

            var filterSVGString = joint.util.filter[filter.name] && joint.util.filter[filter.name](filter.args || {});
            if (!filterSVGString) {
                throw new Error('Non-existing filter ' + filter.name);
            }
            var filterElement = V(filterSVGString);
            filterElement.attr('filterUnits', 'userSpaceOnUse');
            filterElement.node.id = filterId;
            V(this.paper.svg).defs().append(filterElement);
        }

        $selected.each(function() {
            
            V(this).attr('filter', 'url(#' + filterId + ')');
        });
    }