old_contents: export default function selectAll(input, tree, output) {
      //compare the sequenceString being pasted in with what's already stored in the clipboard
      var sequenceLength = tree.get(['sequenceLength']);
      output({
          start: 0,
          end: sequenceLength - 1
      });
  }
new_contents: export default function selectAll(input, tree, output) {
      //compare the sequenceString being pasted in with what's already stored in the clipboard
      var sequenceLength = tree.get(['sequenceLength']);
      output({
          selectionLayer: {
          	start: 0,
          	end: sequenceLength - 2
          }
      });
  }
subject: select all sends correct output