Salesforce Lightning JavaScript Helper method for opening a custom modal window

openModel.js

openModel : function(cmp, componentName, params, modelId, header, cssClass, callback) {
    var modalBody;
    $A.createComponent(componentName, params,
                       function(content, status) {
                           if (status === "SUCCESS") {
                               modalBody = content;
                               cmp.find(modelId).showCustomModal({
                                   header: header,
                                   body: modalBody, 
                                   cssClass: cssClass,
                                   showCloseButton: true,
                                   closeCallback : callback
                               })
                           }
                       });
},