don't show part title if there is only one part

templates/recipe.html

@@ -15,7 +15,9 @@
 <a href="index.html">back</a>
 <h1>{{recipe.title}}</h1>
 {% for part in recipe.parts %}
+{% if recipe.parts|length != 1 %}
 <h2>{{part.title}}</h2>
+{% endif %}
 <h3>Ingredients</h3>
 {% for ing in part.ingredients %}
     <li>{{ingredient(ing)}}</li>