feat: added cleaved_layers property

modeling_bert.py

@@ -177,6 +177,15 @@ class BertEncoder(nn.Module):
         assert 0 <= idx < len(self.layers)
         self._last_layer_idx = idx
 
+    @property
+    def cleaved_layers(self):
+        return len(self.layers) - self.last_layer_idx - 1
+
+    @cleaved_layers.setter
+    def cleaved_layers(self, n: int):
+        assert 0 <= n < len(self.layers)
+        self.last_layer_idx = len(self.layers) - n - 1
+
     @property
     def gradient_checkpointing(self):
         return self._grad_checkpointing