code: public static IAtomContainer fromSignatureString(String signatureString, IChemObjectBuilder coBuilder) {
          ColoredTree tree = AtomSignature.parse(signatureString);
          MoleculeFromSignatureBuilder builder = new MoleculeFromSignatureBuilder(coBuilder);
          builder.makeFromColoredTree(tree);
          return builder.getAtomContainer();
      }
docs: Builder for molecules (rather, for atom containers) from signature
  strings.
  
  @param signatureString the signature string to use
  @param coBuilder {@link IChemObjectBuilder} to build the returned atom container from
  @return an atom container