chore: import upstream snapshot with attribution

decoding/GAD/fairseq/modules/unfold.py

@@ -0,0 +1,19 @@
+# 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.
+
+import torch.nn.functional as F
+
+
+def unfold1d(x, kernel_size, padding_l, pad_value=0):
+    """unfold T x B x C to T x B x C x K"""
+    if kernel_size > 1:
+        T, B, C = x.size()
+        x = F.pad(
+            x, (0, 0, 0, 0, padding_l, kernel_size - 1 - padding_l), value=pad_value
+        )
+        x = x.as_strided((T, B, C, kernel_size), (B * C, C, 1, B * C))
+    else:
+        x = x.unsqueeze(3)
+    return x