code: public DepictionGenerator withHighlight(Iterable<? extends IChemObject> chemObjs, Color color) {
          DepictionGenerator copy = new DepictionGenerator(this);
          for (IChemObject chemObj : chemObjs)
              copy.highlight.put(chemObj, color);
          return copy;
      }
docs: Highlight the provided set of atoms and bonds in the depiction in the
  specified color.
  
  Calling this methods appends to the current highlight buffer. The buffer
  is cleared after each depiction is generated (e.g. {@link #depict(IAtomContainer)}).
  
  @param chemObjs set of atoms and bonds
  @param color    the color to highlight
  @return new generator for method chaining
  @see StandardGenerator#HIGHLIGHT_COLOR