ext/torch/ext.cpp in torch-rb-0.3.0 vs ext/torch/ext.cpp in torch-rb-0.3.1

@@ -350,11 +350,11 @@
       *[](Tensor& self, bool requires_grad) {
         return self.set_requires_grad(requires_grad);
       })
     .define_method(
       "_backward",
-      *[](Tensor& self, Object gradient) {
-        return gradient.is_nil() ? self.backward() : self.backward(from_ruby<torch::Tensor>(gradient));
+      *[](Tensor& self, OptionalTensor gradient, bool create_graph, bool retain_graph) {
+        return self.backward(gradient, create_graph, retain_graph);
       })
     .define_method(
       "grad",
       *[](Tensor& self) {
         return self.grad();