This is the only way to open a file resource.

def open(self):
        """This is the only way to open a file resource."""

        self.__sf = _sftp_open(self.__sftp_session_int, 
                               self.__filepath, 
                               self.access_type_int, 
                               self.__create_mode)

        if self.access_type_is_append is True:
            self.seek(self.filesize)

        return SftpFileObject(self)