def clear_aromatic_S(my_mol):
    """Function to replace an aromatic sulphur with an aromatic oxygen with an unusual isotope
    Takes an RDKit molecule
    Returns the updated molecule"""
    for atom in my_mol.GetAtoms():
        if atom.GetIsAromatic()is True and atom.GetAtomicNum() == 16:
            atom.SetAtomicNum(8)
            atom.SetIsotope(17)
    return my_mol