new_contents: import pymysql
  
  
  class Mysql(object):
  
      def __init__(self, workers_cmd, clicks_cmd, subjects_cmd, **kwargs):
          host = kwargs.get('host', None) or '127.0.0.1'
          port = kwargs.get('port', None) or 3306
          user = kwargs.get('user', None) or 'root'
          passwd = kwargs.get('password', None) or ''
          db = kwargs.get('name', None) or 'project'
  
          self.connection = pymysql.connect(host=host,
                                            port=port,
                                            user=user,
                                            passwd=passwd,
                                            db=db)
          self._workers_cmd = workers_cmd
          self._clicks_cmd = clicks_cmd
          self._subjects_cmd = subjects_cmd
  
      def workers(self):
          self._execute(self._workers_cmd)
  
      def clicks(self):
          self._execute(self._clicks_cmd)
  
      def subjects(self):
          self._execute(self._subjects_cmd)
  
      def _execute(self, cmd):
          cur = self.connection.cursor()
  
          for row in cur.execute(cmd):
              yield row
  
          cur.close()
  
subject: Add mysql adapter