title: Python-MySQLdb, how do you access the exception error-code in `OperationalError`?
body: <p>I need to catch a specific <code>OperationalError</code> exception. The exception text uses the error-code 2006. The library defines the error-codes at <code>MySQLdb.constants.CR.SERVER_GONE_ERROR = 2006</code>.</p>
  
  <p><strong>How do you get the error-code from the exception?</strong></p>
  
  <p>When I check the MySQLdb._mysql_exceptions, there is a definition of the OperationalError exception but it has no constructor or description of how to access the exception error code.</p>