Trying to show an internal note as part of a trigger sending an email to a slack channel.

I have a trigger set up that will send an email via a target to a slack channel when a specific tag is added to the ticket. The premise of this trigger is to notify account managers when their customers ask for a new feature. The integration is working as expected and updating the slack channel but I am having some difficulty with the inclusion of internal (private) notes. 

The trigger includes placeholders such as ticket id, org name and the ticket url. But I also want it to include an internal note left by one of our support agents that briefly outlines the customer feature request, so that our account managers can see exactly what the request is without reading through the whole ticket.

As far as I can tell, there is no internal comment placeholder so I tried to use some liquid markup to fix this but I've had no luck.  Any suggestions or amendments welcome. 
 

{{ticket.follower_names}},


Ticket {{ticket.id}} from {{ticket.organization.name}} has a feature request. 


The details of the feature request are as follows:

{% for comment in ticket.comments %}

  {% if comment.is_public == false %}
  
    {{ comment.value}}
   
   
  {% endif %}
{% endfor %}


View the ticket here:

https://{{ticket.url}}