@Q:
RETURN UNSHIFT( [ <span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span> ], <span class="hljs-number">4</span> )

@R
[
  [
    <span class="hljs-number">4</span>,
    <span class="hljs-number">1</span>,
    <span class="hljs-number">2</span>,
    <span class="hljs-number">3</span>
  ]
]