chore: import upstream snapshot with attribution

decoding/GAD/fairseq/data/num_samples_dataset.py

@@ -0,0 +1,17 @@
+# 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 FairseqDataset
+
+
+class NumSamplesDataset(FairseqDataset):
+    def __getitem__(self, index):
+        return 1
+
+    def __len__(self):
+        return 0
+
+    def collater(self, samples):
+        return sum(samples)