{% comment %}
    Find previous and next episodes (if any).
{% endcomment %}
{% for episode in site.episodes  %}
  {% if episode.url == page.url %}
    {% unless forloop.first %}
      {% assign prev_episode = prev %}
    {% endunless %}
    {% unless forloop.last %}
      {% assign next_episode = site.episodes[forloop.index] %}
    {% endunless %}
  {% endif %}
  {% assign prev = episode %}
{% endfor %}