code: private IAtom[] getAtoms(IAtom focus, IAtom substituent, IAtom otherFocus) {
          IAtom otherSubstituent = focus;
          for (int w : graph[atomToIndex.get(focus)]) {
              IAtom atom = container.getAtom(w);
              if (!atom.equals(substituent) && !atom.equals(otherFocus)) otherSubstituent = atom;
          }
          return new IAtom[]{substituent, otherSubstituent, otherFocus};
      }
docs: Create an array of three atoms for a side of the double bond. This is
  used to determine the 'winding' of one side of the double bond.
  
  @param focus       a double bonded atom
  @param substituent the substituent we know the configuration of
  @param otherFocus  the other focus (i.e. the atom focus is double bonded
  to)
  @return 3 atoms arranged as, substituent, other substituent and other
  focus. if the focus atom has an implicit hydrogen the other
  substituent is the focus.