title: unique values in django template
body: <p>Hi I am working django oscar and working on a functions which selects values of attribute. I want {{product.examination_filter }} to be list of values without duplicates.  </p>
  
  <p>HTML :</p>
  
  <pre><code>&lt;div class="portion"&gt;
          {% for product in products%}
                       {{product.examination_filter }}                   
          {% endfor %}                                    
  &lt;/div&gt;
  </code></pre>
  
  <p>Models.py </p>
  
  <pre><code>class Product(AbstractProduct):
  from django.db import models
  from oscar.apps.catalogue.abstract_models import AbstractProduct
  
  def examination_filter(self):
      attributes = self.attribute_values.all()
      for attribute in attributes:
          if attribute.attribute.name == 'examination':
              return (attribute.value)
  </code></pre>
  
  <p>I am getting duplicate values because of for loop on each product. How can I make a unique list of values in django template language ? Note that views.py is handeled by oscar and I am getting products (group of product) on my html from oscar logic. Please help basically i want this values to be displayed as filters for products on webpage.</p>