chore: import upstream snapshot with attribution

decoding/GAD/fairseq/data/strip_token_dataset.py

@@ -0,0 +1,20 @@
+# Copyright (c) Facebook, Inc. and its affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+
+from . import BaseWrapperDataset
+
+
+class StripTokenDataset(BaseWrapperDataset):
+    def __init__(self, dataset, id_to_strip):
+        super().__init__(dataset)
+        self.id_to_strip = id_to_strip
+
+    def __getitem__(self, index):
+        item = self.dataset[index]
+        while len(item) > 0 and item[-1] == self.id_to_strip:
+            item = item[:-1]
+        while len(item) > 0 and item[0] == self.id_to_strip:
+            item = item[1:]
+        return item