def METHOD_NAME(atom_list: List):
    atom_counters = {}
    atom_ind = []
    for atom_type in atom_list:
        if atom_type not in atom_counters:
            atom_counters[atom_type] = 1
        atom_ind.append(atom_counters[atom_type])
        atom_counters[atom_type] += 1
    return atom_ind