[web2py] How to Truncate a Post or display post exceprts

[ola . dipo30]

I am new to web2py and was wondering how I can go about displaying a post 
excerpts on a page. e.g. {{=WIKI(post.body|truncate:30)}} or something 
similar to that?  Thanks in advance. 
 
{{ for post in posts:}}
   <h2>
     <a href="{{=URL(r=request,f='view_post',args=post.id)}}">
       {{=post.title}}
     </a>
   </h2>
{{=WIKI(post.body|truncate:30)}}
{{pass}}

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