def oxygen_to_fuel(self): mol = Molecule().from_smiles(self.fuel['smiles']) atom_dict = mol.get_element_count() oxygen_to_fuel = 0 for element, counts in atom_dict.items(): if element == 'C': oxygen_to_fuel += counts elif element == 'H': oxygen_to_fuel += counts / 4 elif element == 'O': oxygen_to_fuel -= counts / 2 return oxygen_to_fuel