code: function checkFile(peripheralId, callback) {
    if (overWriteServices) {
      callback(false);
    } else {
      fs.stat(devicesPath + '/' + peripheralId + '.srv.json', function(err, stat) {
        if(err == null) {
          callback(true);
          //  console.log('File exists');
        } else {
          callback(false)
        }
      });   
    }
  }
docs: check if the services file exists