try:
            monomer_structure = monomer_form.get_structure()[0]
            if monomer_form.get_formula() != OpenBabelUtils.get_formula(monomer_structure):
                errors.append('Monomeric form of {} has incorrect formula: {} != {}'.format(
                    monomer.id, str(monomer_form.get_formula()), str(OpenBabelUtils.get_formula(monomer_structure))))