code: function onEnter(assignment) {
    // TODO: GCLI doesn't support passing a context to notifications of cursor
    // position, so onEnter/onLeave/onChange are disabled below until we fix this
    assignment.highlighter = new Highlighter(context.environment.window.document);
    assignment.highlighter.nodelist = assignment.conversion.matches;
  }
docs: Helper functions to be attached to the prototypes of NodeType and
  NodeListType to allow terminal to tell us which nodes should be highlighted