title: How to fix issues with E402?
body: <p>We are trying to fix issues with PEP8 E402.</p>
  
  <p>Mostly our code is broken on:</p>
  
  <pre><code>import os
  os.environ['LIB_CAN_THROW_ERROR_ON_IMPORT'] = 2
  import lib
  os.environ['LIB_CAN_THROW_ERROR_ON_IMPORT'] = 0 # back
  </code></pre>
  
  <p>-</p>
  
  <pre><code>if sys.version_info[0] &gt; 2:
      import python3lib
  else:
      import python2lib
  </code></pre>
  
  <p>-</p>
  
  <pre><code>try:
      import lib
  except:
      print('lib is required')
      sys.exit(1)
  </code></pre>
  
  <p>How to solve these violations?</p>