private static void WriteBond(
TextWriter writer, Molecule molecule, int i)
{
int f = molecule.GetFirstInBond(i) + 1;
int s = molecule.GetSecondInBond(i) + 1;
int o = molecule.GetBondOrderAsInt(i);
writer.Write($"{f,3:D}{s,3:D}{o,3:D} 0 0 0 0");
writer.Write('\n');
}
