i(..) indexing sugar (partial).

- Only range, and select (no tensor_select)
- No negative indexing

candle-core/src/tensor.rs

@@ -444,6 +444,7 @@ impl Tensor {
                 len,
             })?
         }
+        println!("Narrow  {start:?} - {} - {len} - {dims:?}", dims[dim]);
         if start == 0 && dims[dim] == len {
             Ok(self.clone())
         } else {
@@ -452,10 +453,11 @@ impl Tensor {
             } else {
                 None
             };
+            let layout = self.layout().narrow(dim, start, len)?;
             let tensor_ = Tensor_ {
                 id: TensorId::new(),
                 storage: self.storage.clone(),
-                layout: self.layout().narrow(dim, start, len)?,
+                layout,
                 op,
                 is_variable: false,
             };