[Models] Improve iteration over layers (#19497)

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

vllm/model_executor/models/qwen2_moe.py

@@ -25,6 +25,7 @@
 # limitations under the License.
 """Inference-only Qwen2MoE model compatible with HuggingFace weights."""
 from collections.abc import Iterable
+from itertools import islice
 from typing import Any, Optional, Union
 
 import torch
@@ -381,7 +382,7 @@ class Qwen2MoeModel(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, residual)
         if not get_pp_group().is_last_rank:
             return IntermediateTensors({