docs: def to_rdmol(mol):
      """Convert molecule to RDMol"""
      rwmol = Chem.RWMol(Chem.MolFromSmiles(''))
      key_to_idx = {}
      bond_type = {1: Chem.BondType.SINGLE,
                   2: Chem.BondType.DOUBLE,
                   3: Chem.BondType.TRIPLE}
      conf = Chem.Conformer(rwmol.GetNumAtoms())
      for k, a in mol.atoms_iter():
          i = rwmol.AddAtom(Chem.Atom(atom_number(a.symbol)))
          key_to_idx[k] = i
          conf.SetAtomPosition(i, a.coords)
      rwmol.AddConformer(conf)
      for u, v, b in mol.bonds_iter():
          ui = key_to_idx[u]
          vi = key_to_idx[v]
          rwmol.AddBond(ui, vi, bond_type[b.order])
      Chem.GetSSSR(rwmol)  # Ring recognition is required for fingerprint
      rwmol.UpdatePropertyCache(strict=False)
      return rwmol.GetMol()