<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _warn_deprecated_outside_JSONField(self):
 # pylint: disable=invalid-name """Certain methods will be moved to JSONField. This warning marks calls when the object is not derived from that class. """

        if not isinstance(self, JSONField) and not self.warned:
            warnings.warn(
                "Deprecated. JSONifiable fields should derive from JSONField ({name})".format(name=self.name),
                DeprecationWarning,
                stacklevel=3
            )
            self.warned = True