[Models] Improve iteration over layers (#19497)

Signed-off-by: Lukas Geiger <lukas.geiger94@gmail.com>

vllm/model_executor/models/chameleon.py

@@ -3,6 +3,7 @@
 
 from collections.abc import Iterable, Mapping, Sequence
 from functools import cached_property
+from itertools import islice
 from typing import Annotated, Any, Literal, Optional, Union
 
 import torch
@@ -914,7 +915,7 @@ class ChameleonModel(nn.Module):
             assert intermediate_tensors is not None
             hidden_states = intermediate_tensors["hidden_states"]
             residual = intermediate_tensors["residual"]
-        for layer in self.layers[self.start_layer:self.end_layer]:
+        for layer in islice(self.layers, self.start_layer, self.end_layer):
             hidden_states, residual = layer(
                 positions,
                 hidden_states,