for (key in this.paper.customAttributes) if (this.paper.customAttributes[has](key) && params[has](key) && R.is(this.paper.customAttributes[key], "function")) {
            var par = this.paper.customAttributes[key].apply(this, [].concat(params[key]));
            this.attrs[key] = params[key];
            for (var subkey in par) if (par[has](subkey)) {
                params[subkey] = par[subkey];