title: Saving a Binary tree to a file
body: <p>I have a non-balanced (not binary-search) binary tree
  Need to incode (and later decode) it to txt file.
  How can I do it in efficient way?</p>
  
  <p>I found this <a href="https://stackoverflow.com/questions/3606912/binary-tree-transfer">link</a> 
  which talks about similar (same) problem,but it is obvious for me</p>