code: function makeVarMerge(names) {
    names = names.map(function(name) {
      return memberExpression(identifier(name), identifier('vars'), false);
    });
    var expr = callExpression(
      identifier('xcss.runtime.merge'),
      [identifier('vars')].concat(names));
    return expressionStatement(expr);
  }
docs: xcss.runtime.merge(vars, $name.vars)