def mixture_check(unlabeled_smiles):
    """
    Aborts the prediction if the SMILES contains mixtures.

    Parameters
    ----------
    unlabeled_smiles : str
        SMILES string describing a compound.

    Returns
    -------
    str :
        the SMILES if it's not disconnected. Raises an error otherwise.

    """
    if "." in unlabeled_smiles:
        raise ValueError(
            "SMILES containing mixtures cannot be processed. Program aborting"
        )
    else:
        return unlabeled_smiles