code: function (callback) {
      return function (new_method, assert_method, arity) {
          return function () {
              var message = arguments[arity - 1];
              var a = exports.assertion({method: new_method, message: message});
              try {
                  assert[assert_method].apply(null, arguments);
              }
              catch (e) {
                  a.error = e;
              }
              callback(a);
          };
      };
  }
docs: Create a wrapper function for assert module methods. Executes a callback
  after the it's complete with an assertion object representing the result.
  
  @param {Function} callback
  @api private