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

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