def sftp(self):
        """
        Method which lazily establishes SFTP connection if one is not established yet when this
        variable is accessed.
        """
        if not self.sftp_client:
            self.sftp_client = self.client.open_sftp()

        return self.sftp_client

        Method which lazily establishes SFTP connection if one is not established yet when this
        variable is accessed.
        
st2common/st2common/runners/paramiko_ssh.py