How can I make a block helper for meteor. I need something similar to django's ifchanged template tag.

ifchanged

{{#each meetings}}
  {{#ifchanged date}}
    </ul>
    <div class="date">{{date}}</div>
    <ul class="list-group">
  {{/ifchanged}}
  <li>{{title}}</li>
{{/each}}

Given this:[{title:"Foo",date:"Today"}, {title:"Bar",date:"Today"}, {title:"Foo",date:"Tomorrow"}, {title:"Bar",date:"Tomorrow"}]

Would produce:
<div class="date">Today</div>
<ul class="list-group">
  <li>Foo</li>
  <li>Bar</li>
</ul>
<div class="date">Tomorrow</div>
<ul class="list-group">
  <li>Foo</li>
  <li>Bar</li>
</ul>

This helper seems to work as long as I reset lastValue when I'm done:
lastValue = "";
Handlebars.registerHelper('ifchanged', function(value, options) {
  if(lastValue != value){
    lastValue = value;
    return options.fn(this);
  }
});

lastValue = "";
Handlebars.registerHelper('ifchanged', function(value, options) {
if(lastValue != value){
lastValue = value;
return options.fn(this);
}
});