code: def get_statistics(self, prefix=''):
          
          return ['%-7s %s %s' % (self.counters[key], key, self.messages[key])
                  for key in sorted(self.messages) if key.startswith(prefix)]
docs: Get statistics for message codes that start with the prefix.
  
          prefix='' matches all errors and warnings
          prefix='E' matches all errors
          prefix='W' matches all warnings
          prefix='E4' matches all errors that have to do with imports