code: function mergeItemLists( targetList, sourceList, page ) {
     sourceList.forEach( item => {
        if( item.insertBeforeId ) {
           for( let i = 0, length = targetList.length; i < length; ++i ) {
              if( targetList[ i ].id === item.insertBeforeId ) {
                 targetList.splice( i, 0, item );
                 return;
              }
           }
  
           throw formatError( page, `No id found that matches insertBeforeId value "${item.insertBeforeId}"` );
        }
        targetList.push( item );
     } );
  }
docs: ////////////////////////////////////////////////////////////////////////////////////////////////////////////  Common functionality and utility functions  ////////////////////////////////////////////////////////////////////////////////////////////////////////////