code: function exec() {
  		var result;
  
  		while(scripts.length) {
  			var script = scripts.shift();
  			if(typeof(script) == 'function') {
  				result = script();
  				if(result && typeof(result) == 'object' && typeof(result.then) == 'function') {
  					result.then(exec);
  					break;
  				}
  			} else {
  				eval(script);
  			}
  		}
  	}
docs: Try to load a single module from multiple possible addresses.
  
  @param { number } num - Index of module in deps to maintain order.
  @param { string } key - Key for successfully resolved address cache.
  @param { string[] } urls - Addresses in order of decreasing preference.