def METHOD_NAME(self):
    """ Check that this model is being used correctly. """
    # These could probably be replaced with constraints in Django 4.1+
    if self.user.id != self.content.user.id:
        raise ValidationError("User ID mismatch.")
    if self.content.purpose != CLIPBOARD_PURPOSE:
        raise ValidationError(
            f"StagedContent.purpose must be '{CLIPBOARD_PURPOSE}' to use it as clipboard content."
        )