    def forward(self, x: torch.Tensor):
        """Add positional encoding.
        Args:
            x : Input tensor T X B X C.
        Returns:
            torch.Tensor: Encoded tensor T X B X C.

        """
        x = x.transpose(0, 1)  # Change TBC to BTC
        self.extend_pe(x)
        pos_emb = self.pe[
            :,
            self.pe.size(1) // 2 - x.size(1) + 1 : self.pe.size(1) // 2 + x.size(1),
        ]
        pos_emb = pos_emb.transpose(0, 1)  # change to TBC
        return pos_emb
Add positional encoding.
Args:
x : Input tensor T X B X C.
Returns:
torch.Tensor: Encoded tensor T X B X C.
fairseq/modules/positional_encoding.py