explain duck shapes

Author: sayakpaul

tests/models/test_modeling_common.py

@@ -2262,6 +2262,9 @@ def test_hotswapping_compile_on_different_shapes(self, rank0, rank1):
         different_shapes_for_compilation = self.different_shapes_for_compilation
         if different_shapes_for_compilation is None:
             pytest.skip(f"Skipping as `different_shapes_for_compilation` is not set for {self.__class__.__name__}.")
+        # Specifying `use_duck_shape=False` instructs the compiler if it should use the same symbolic
+        # variable to represent input sizes that are the same. For more details,
+        # check out this [comment](https://github.com/huggingface/diffusers/pull/11327#discussion_r2047659790).
         torch.fx.experimental._config.use_duck_shape = False
 
         target_modules = ["to_q", "to_k", "to_v", "to_out.0"]