title: Add key in python dict, but rename if it exists
body: <p>I have a simple script:</p>
  <pre><code>d = {}
  
  keys = ['f', 'f', 'f', 'f']
  
  for k in keys:
      if k in d:
          k += '_copy'
          
      d[k] = 'test'
      
  print(d)
  </code></pre>
  <p>And it produce output like this:</p>
  <pre><code>{'f': 'test', 'f_copy': 'test'}
  </code></pre>
  <p>but I need to rename key by adding suffix</p>
  <blockquote>
  <p>_copy</p>
  </blockquote>
  <p>every time I add key that already exists. So output should be something like this:</p>
  <pre><code>{'f': 'test', 'f_copy': 'test', 'f_copy_copy': 'test', 'f_copy_copy_copy': 'test'}
  </code></pre>
  <p>How can I do this?</p>