title: How to set MDB_NOTLS mode in python lmdb
body: <p>In lmdb docs: 
  "MDB_NOTLS mode is used exclusively, which allows read transactions to freely migrate across threads and for a single thread to maintain multiple read transactions. This enables mostly care-free use of read transactions, for example when using gevent."</p>
  
  <p>But there is no manual how to set it in python.</p>
  
  <p>I tried: </p>
  
  <pre><code>import os
  os.environ['MDB_NOTLS'] = '1'
  import lmdb
  </code></pre>
  
  <p>Is it right?</p>