title: python modify item in list, save back in list
body: <p>I have a hunch that I need to access an item in a list (of strings), modify that item (as a string), and put it back in the list in the same index</p>
  
  <p>I'm having difficulty getting an item back into the same index</p>
  
  <pre><code>for item in list:
      if "foo" in item:
          item = replace_all(item, replaceDictionary)
          list[item] = item
          print item
  </code></pre>
  
  <p>now I get an error </p>
  
  <pre><code>TypeError: list indices must be integers, not str
  </code></pre>
  
  <p>due to this line <code>list[item] = item</code></p>
  
  <p>which makes sense! but I do not know how to put the item back into the list at that same index using python</p>
  
  <p>what is the syntax for this? Ideally the for loop can keep track of the index I am currently at</p>