code: function _setFilter(filt) {
      filt = filt.trim()
      if (filt === 'all')
        this.filter = filt
      else if (filt in _filters) {
        if (this.filter !== 'all' && this.filter.indexOf(filt) < 0)
          this.filter.push(filt)
      }
      else this.invalid('filter', filt)
    }
docs: Enable filters for comments, 'all' enable all filters