title: unable to run Mozart code
body: <pre><code>local MainSum in
    fun {MainSum N}
      local Sum in 
        fun {Sum N Acc} 
          if N==0 then Acc 
            else Acc+{Sum N-1 N*N} 
          end 
        end 
       {Sum 5 0}
       end
    end
  end
  </code></pre>
  
  <p>When i Try this codes it shows following error</p>
  
  <pre><code>%************************** syntax error ************************
  %**
  %** nesting marker expected as designator of nested function
  %**
  %** in file "exercise.oz", line  2, column 7
  %** ------------------ rejected (1 error)
  </code></pre>