Edit in JSFiddle

var code = document.getElementById('code');
var blocks = CodeMirrorBlocks.fromTextArea(code, 'wescheme');
blocks.setBlockMode(true)
$('#toggle').click(function() { blocks.toggleBlockMode(); });

<script src="https://bootstrapworld.github.io/codemirror-blocks/dist/CodeMirrorBlocks-all.js"></script>
<textarea id="code" style="height:200px">
(+ (* 7 2) (- 5 7))
</textarea>
<button id="toggle" class="btn btn-default pull-right">
Toggle Block Mode
</button>