docs: function() {
      var tok = this.scanEndOfLine(/^case +([^\n]+)/, 'case');
      if (tok) {
        this.incrementColumn(-tok.val.length);
        this.assertExpression(tok.val);
        this.incrementColumn(tok.val.length);
        this.tokens.push(tok);
        return true;
      }
      if (this.scan(/^case\b/)) {
        this.error('NO_CASE_EXPRESSION', 'missing expression for case');
      }
    }