text: 
  define('a',{
      name: 'a'
  });
  define('c',{
      name: 'c'
  });
  define('b',{
      name: 'b'
  });
  define('d',{
      name: 'd'
  });
  
  
  define('main',['require', 'a'], function(require, a) {
  
     if (has('needC')) {
          require(['c'], function (c) {
  
          });
     } else if (has('needB')) {
          require(['b'], function (b) {
  
          });
     } else {
          require(['d'], function (d) {
  
          });
     }
  });