Updated sentence embeddings example (#263)

* Added conversion information for Distil-based sentence embedding models

* Fix Clippy warnings

examples/sentence_embeddings_local.rs

@@ -9,6 +9,19 @@ use rust_bert::pipelines::sentence_embeddings::SentenceEmbeddingsBuilder;
 ///   ```sh
 ///   python ./utils/convert_model.py resources/all-MiniLM-L12-v2/pytorch_model.bin
 ///   ```
+///
+/// For models missing the prefix in their saved weights (e.g. Distil-based models), the
+/// conversion needs to be updated to include this prefix so that the weights can be found:
+///   ```sh
+///   python ./utils/convert_model.py resources/path/to/pytorch_model.bin --prefix distilbert.
+///   ```
+///
+/// For models including a dense projection layer (e.g. Distil-based models), these weights
+/// need to be converted as well:
+/// ```sh
+///   python ../utils/convert_model.py  resources/path/to/2_Dense/pytorch_model.bin --suffix
+/// ```
+///
 fn main() -> anyhow::Result<()> {
     // Set-up sentence embeddings model
     let model = SentenceEmbeddingsBuilder::local("resources/all-MiniLM-L12-v2")

src/m2m_100/m2m_100_model.rs

@@ -119,7 +119,7 @@ fn _shift_tokens_right(
         (Kind::Int64, input_ids.device()),
     );
     let _ = shifted_input_ids.select(1, 0).fill_(decoder_start_token_id);
-    let _ = shifted_input_ids
+    shifted_input_ids
         .slice(1, 1, *shifted_input_ids.size().last().unwrap(), 1)
         .copy_(&input_ids.slice(1, 0, *input_ids.size().last().unwrap() - 1, 1));
     shifted_input_ids.masked_fill(&shifted_input_ids.eq(-100), pad_token_id)

src/pegasus/pegasus_model.rs

@@ -77,7 +77,7 @@ fn _shift_tokens_right(
         input_ids.size().as_slice(),
         (input_ids.kind(), input_ids.device()),
     );
-    let _ = shifted_input_ids
+    shifted_input_ids
         .slice(1, 1, input_ids_length, 1)
         .copy_(&input_ids.slice(1, 0, input_ids_length - 1, 1));