docs: function(expr, options) {
                      var value;
                      // if it's a function, wrap its value in a compute
                      // that will only change values from true to false
                      if (can.isFunction(expr)) {
                          value = can.compute.truthy(expr)();
                      } else {
                          value = !! Mustache.resolve(expr);
                      }
  
                      if (value) {
                          return options.fn(options.contexts || this);
                      } else {
                          return options.inverse(options.contexts || this);
                      }
                  }