code: function conditional(test, success, failure, callback) {
          ///<summary>
          /// INFO: use cases:
          ///    head.test(condition, null       , "file.NOk" , callback);
          ///    head.test(condition, "fileOk.js", null       , callback);
          ///    head.test(condition, "fileOk.js", "file.NOk" , callback);
          ///    head.test(condition, "fileOk.js", ["file.NOk", "file.NOk"], callback);
          ///    head.test({
          ///               test    : condition,
          ///               success : [{ label1: "file1Ok.js"  }, { label2: "file2Ok.js" }],
          ///               failure : [{ label1: "file1NOk.js" }, { label2: "file2NOk.js" }],
          ///               callback: callback
          ///    );
          ///    head.test({
          ///               test    : condition,
          ///               success : ["file1Ok.js" , "file2Ok.js"],
          ///               failure : ["file1NOk.js", "file2NOk.js"],
          ///               callback: callback
          ///    );
          ///</summary>
          var obj = (typeof test === "object") ? test : {
              test: test,
              success: !!success ? isArray(success) ? success : [success] : false,
              failure: !!failure ? isArray(failure) ? failure : [failure] : false,
              callback: callback || noop
          };
  
          // Test Passed ?
          var passed = !!obj.test;
  
          // Do we have a success case
          if (passed && !!obj.success) {
              obj.success.push(obj.callback);
              api.load.apply(null, obj.success);
          }
          // Do we have a fail case
          else if (!passed && !!obj.failure) {
              obj.failure.push(obj.callback);
              api.load.apply(null, obj.failure);
          }
          else {
              callback();
          }
  
          return api;
      }
docs: #endregion