public static OBMol molecule_merge(OBMol mol1, OBAtom a, OBMol mol2, OBAtom b)
        {
            //takes two molecules and two atoms in each molecule and
            //assuming atoms are in the same place, delete one atom and copy bond to the other
            //a
            //foreach(OBBond bond in b.Bonds())
            //{

            //}

            int keepid     = Convert.ToInt32(a.GetIdx());
            int todeleteid = Convert.ToInt32(b.GetIdx());
            //var bonds = b.Bonds();
            List <OBBond> bondlist = new List <OBBond>();

            foreach (OBBond bon in b.Bonds())
            {
                bondlist.Add(bon);
            }
            OBBond bond      = bondlist[0];
            int    connectid = (int)bond.GetNbrAtomIdx(b);
            int    prevatms  = (int)mol1.NumAtoms(); //number of atoms before we combine things

            //OBMol mol3 = new OBMol ();

            mol1 = addmol(mol2, mol1);
            mol1.BeginModify();
            OBAtom keep      = mol1.GetAtom(keepid);
            OBAtom todelete  = mol1.GetAtom(todeleteid + prevatms);
            OBAtom toconnect = mol1.GetAtom(connectid + prevatms);
            OBBond newbond   = new OBBond();

            newbond.SetBegin(keep);
            newbond.SetEnd(toconnect);
            newbond.SetBO(1);
            mol1.AddBond(newbond);
            mol1.DeleteAtom(todelete);
            //OBAtom= atom1
            //var a = map2[0];
            //int c1 = (int)(map1[1]);
            //int c2 = (int)(map2[1] + prevatms);
            //int h1 = (int)(map1[0]);
            ///int h2 = (int)(map2[0] + prevatms);
            //OBAtom carbon1 = mol1.GetAtom(c1);
            //OBAtom carbon2 = mol1.GetAtom(c2);
            //OBAtom hydrogen1 = mol1.GetAtom(h1);
            ///OBAtom hydrogen2 = mol1.GetAtom(h2);
            //OBBuilder.Connect(mol1, c1, c2);//connect fragments
            //mol1.DeleteAtom(hydrogen1);
            //mol1.DeleteAtom(hydrogen2);
            mol1.EndModify();
            return(mol1);
        }
        public static OBMol molecule_merge(OBMol mol1, OBAtom tokeep, OBAtom todelete)
        {
            //takes a molecule and two atoms in the molecule and
            //assuming atoms are in the same place, delete one atom and copy bond to the other

            mol1.BeginModify();
            uint todeleteid = todelete.GetIdx();
            //var bonds = b.Bonds();


            List <OBBond> bondlist = new List <OBBond>();

            foreach (OBBond bon in todelete.Bonds())
            {
                bondlist.Add(bon);
            }

            foreach (OBBond bon in bondlist)
            {
                mol1.AddBond((int)tokeep.GetIdx(), (int)bon.GetNbrAtomIdx(todelete), (int)bon.GetBondOrder());
            }
            //writeatominfotoscreen(mol1);
            //int connectid = (int)bond.GetNbrAtomIdx(b);


            //todelete = mol1.GetAtomById(todeleteid);
            ///OBAtom toconnect = mol1.GetAtom(connectid);
            //OBBond newbond = new OBBond();
            //newbond.SetBegin(keep);
            //newbond.SetEnd(toconnect);
            //newbond.SetBO(1);
            //mol1.AddBond(newbond);
            mol1.DeleteAtom(todelete);

            mol1.EndModify();
            return(mol1);
        }
        public static OBMol addmol(OBMol source, OBMol dest)
        {
            //combines two OBMols into one molecule
            // this is designed to do the same thing as the += operator in mol.cpp, in other words this implements functionality present in openbabel, but not in the C# api
            dest.BeginModify();
            uint prevatms = dest.NumAtoms();
            uint nextatms = source.NumAtoms();

            // First, handle atoms and bonds
            foreach (OBAtom atom in source.Atoms())
            {
                atom.SetId(0); ////Need to remove ID which relates to source mol rather than this mol// But in the C++ it had a NoId thing I couldn't figure out
                dest.AddAtom(atom);
                //var foooo = dest.Atoms ();
            }
            //writeatominfotoscreen (dest);
            foreach (OBBond bond in source.Bonds())
            {
                bond.SetId(0);

                dest.AddBond((int)(bond.GetBeginAtomIdx() + prevatms), (int)(bond.GetEndAtomIdx() + prevatms),
                             (int)bond.GetBO(), (int)bond.GetFlags());
            }

            //don't really understand what they mean by residues
            //I think it's an amino acid or nucleotide so you can build up proteins and stuff?
            //don't think I'm going to use them either, but it might be useful

            foreach (OBResidue residue in source.Residues())
            {
                OBResidue newres = new OBResidue();
                dest.AddResidue(newres);

                OBResidueAtomIter ai = new OBResidueAtomIter(residue);
                //dammit why didn't they implement a residue.atoms sort of thing? I don't want to play with enumerators
                ////#define FOR_ATOMS_OF_RESIDUE(a,r) for( OBResidueAtomIter a(r); a; ++a )
                while (ai.MoveNext())
                {
                    OBAtom resatom = new OBAtom();
                    resatom = ai.Current;
                    // This is the equivalent atom in our combined molecule
                    OBAtom atom = dest.GetAtom((int)(resatom.GetIdx() + prevatms));
                    // So we add this to the last-added residue
                    // (i.e., what we just copied)
                    //[dest.NumResidues () - 1]

                    var res = dest.Residues().GetEnumerator();
                    while (!res.MoveNext())
                    {
                    }                           //move to the last residue
                    res.Current.AddAtom(atom);

                    //var item = dest.Cast<RMSRequestProcessor.RMSMedia> ().ElementAt (1);
                }


                //for(OBAtom resatom in )
            }
            dest.EndModify();

            return(dest);
        }