{%- assign permalinkWithoutLang = page.url | split: "/" | slice: 2 | join: "/" %}
{%- for alt in languages %}
  {%- if alt.code != lang %}
    <link
      rel="alternate"
      hreflang="{{alt.code}}"
      href="/{{alt.code}}/{{permalinkWithoutLang}}" />
  {%- endif %}
{%- endfor %}