s. `X` is a</span>
<span class="sd">    sequence of integers representing the SMILES tokens, and `y` is the same</span>
<span class="sd">    sequence shifted by one position to the right.</span>

<span class="sd">    Parameters</span>
<span class="sd">    ----------</span>
<span class="sd">    idx : int</span>
<span class="sd">        Index of the molecule to return.</span>

<span class="sd">    Returns</span>
<span class="sd">    -------</span>
<span class="sd">    Tuple[torch.Tensor, torch.Tensor]</span>
