def __getitem__(self, index):
        """
        Returns a single noisy sample. Multiple samples are fed to the collater
        create a noising dataset batch.
        """
        src_tokens = self.src_dataset[index]
        src_lengths = torch.LongTensor([len(src_tokens)])
        src_tokens = src_tokens.unsqueeze(0)

        # Transpose src tokens to fit expected shape of x in noising function
        # (batch size, sequence length) -> (sequence length, batch size)
        src_tokens_t = torch.t(src_tokens)

        with data_utils.numpy_seed(self.seed + index):
            noisy_src_tokens = self.noiser.noising(src_tokens_t, src_lengths)

        # Transpose back to expected src_tokens format
        # (sequence length, 1) -> (1, sequence length)
        noisy_src_tokens = torch.t(noisy_src_tokens)
        return noisy_src_tokens[0]

        Returns a single noisy sample. Multiple samples are fed to the collater
        create a noising dataset batch.
        
structured_prompting/fairseq-version/fairseq/fairseq/data/noising.py