var traineePromise = $().SPServices.SPGetListItemsJson({
        webURL: _spPageContextInfo.webAbsoluteUrl,
        CAMLQuery: "<Query><Where>
                 <And>
                     "+ workflowname + "
                     <Or>
                      <Eq><FieldRef Name='AssignedTo'/><Value Type='Integer'>"+ _spPageContextInfo.userId + "</Value></Eq>
                      <Membership Type='CurrentUserGroups'><FieldRef Name='AssignedTo'/></Membership>
                     </Or>
                 </And>
             </Where></Query>",
        listName: "Workflow Tasks"
    });

    $.when(traineePromise).done(function () {
     ...
       })