Differentiate a string from an array when looping over mixed values in nunjucks

string_from_array.njk

{% set mixed_object = {
                        key_1: 'Delta',
                        key_2: 'Epsilon',
                        key_3: ['Zeta', 'Eta', 'Theta', 'Iota']
                      } %}
{% for key, value in mixed_objct %}
  {% if value[0].length > 1 %}
    {# This is an array, do array stuff with it #}
    {{ value | join('<br>') | safe }}
   {% else %}
    {# This is just a string, array filters will break it, do string stuff with it #}
    {{ value }}
   {% endif %}
{% endfor %}