title: Python: Replace ith occurence of x with ith element in list
body: <p><br>
  Suppose we have a string <code>a = "01000111000011"</code> with <code>n=5 "1"</code>s. The <em>ith</em> <code>"1"</code>, I would like to replace with the <em>ith</em> character in <code>"ORANGE"</code>.
  My result should look like:</p>
  
  <pre><code>b = "0O000RAN0000GE"
  </code></pre>
  
  <p>What could be the finest way to solve this problem in Python? Is it possible to bind an index to each substitution?</p>
  
  <p>Many thanks!
  Helga</p>