title: Pass a context variable through an inclusion tag
body: <p>Performing a check to see whether or not a user is attending or not. How do I pass the context variable <code>is_attending</code> to the template without getting a syntax error on <code>'is_attending': context['is_attending']</code>? The check is basically for styling divs and whatnot. What am I doing wrong?</p>
  
  <p><strong>template:</strong></p>
  
  <pre><code>{% for event in upcoming %}
      {% registration %}
  
      {% if is_attending %}
           Registered!
      {% else %}
            Register button
      {% endif %}
  
      yadda yadda divs...
  {% endfor %} 
  </code></pre>
  
  <p><strong>filters.py</strong></p>
  
  <pre><code>@register.inclusion_tag('events/list.html', takes_context=True)
  def registration(context, event):
      request = context['request']
      profile = Profile.objects.get(user=request.user)
      attendees = [a.profile for a in Attendee.objects.filter(event=event)]
      if profile in attendees:
          'is_attending': context['is_attending']
          return is_attending
      else:
          return ''
  </code></pre>
  
  <p>Thank you!</p>