title: Need to add an element at the start of an iterator in python
body: <p>I have a program as follows:</p>
  
  <pre><code>a=reader.next()
  if *some condition holds*:
      #Do some processing and continue the iteration
  else:
      #Append the variable a back to the iterator
      #That is nullify the operation *a=reader.next()*
  </code></pre>
  
  <p>How do I add an element to the start of the iterator? 
  (Or is there an easier way to do this?)</p>
  
  <p>EDIT: OK let me put it this way. I need the next element in an iterator without removing it.
   How do I do this>?</p>