Combine Multiple Spreadsheets into One Google Sheet

function addMenu()
{
 var menu = SpreadsheetApp.getUi().createMenu('Custom');
 menu.addItem('Copy Data', 'getData');
 menu.addToUi();
}

function onOpen(e)
{
 addMenu(); 
}

function getData() {
  
  get_files = ['SpreadSheet Example 1', 'SpreadSheet Example 2'];
  
  var ssa = SpreadsheetApp.getActiveSpreadsheet();
  var copySheet = ssa.getSheetByName('DATA');
  copySheet.getRange('A2:Z').clear();  
  
  for(z = 0; z < get_files.length; z++)
  {
  
    var files = DriveApp.getFilesByName(get_files[z]);
    while (files.hasNext()) 
    {
      var file = files.next();
      break;
    }
  
    var ss = SpreadsheetApp.open(file);
    SpreadsheetApp.setActiveSpreadsheet(ss);
    var sheets = SpreadsheetApp.getActiveSpreadsheet().getSheets();
    
    for(var i = 0; i < sheets.length; i++)
    {  
      var nameSheet = ss.getSheetByName(sheets[i].getName()); 
      var nameRange = nameSheet.getDataRange();
      var nameValues = nameRange.getValues();
      
      for(var y = 1; y < nameValues.length; y++)
      {
        copySheet.appendRow(nameValues[y]); 
      }     
    }    
  }  
}