title: Reformat a Python file to have 4 space indentations
body: <p>I'm editing a Python file that uses two spaces for programmatic indents -  I prefer 4 spaces. In my .vimrc I have the following settings related to indentation:</p>
  
  <pre><code>set tabstop=4                     "Indentation levels every four columns
  set expandtab                     "Convert all tabs typed to spaces
  set shiftwidth=4                  "Indent/outdent by four columns
  set softtabstop=4
  </code></pre>
  
  <p>How do I get Vim to convert all the existing 2 space indents to be 4 space indents?</p>
  
  <p>In other words:</p>
  
  <pre><code>if something:
    dothis()
  </code></pre>
  
  <p>becomes</p>
  
  <pre><code>if something:
      dothis()
  </code></pre>
  
  <p>When I tried gg=G</p>
  
  <pre><code>def check():
    for a in list:
      for  b in list2:
        check(a, b)
        while (len &gt; MAX) :
          poll()
  
    while(len(thelist) &gt; 0) :
      poll()  
  
    return results
  </code></pre>
  
  <p>became</p>
  
  <pre><code>def check():
      for a in list:
      for  b in list2:
      check(a, b)
      while (len &gt; MAX) : 
          poll()
  
          while(len(thelist) &gt; 0) :
              poll()
  
              return results
  </code></pre>