Returns the :class:`Folder <pyOutlook.core.folder.Folder>` this message is in

            >>> account = OutlookAccount('')
            >>> message = account.get_messages()[0]
            >>> message.parent_folder
            Inbox
            >>> message.parent_folder.unread_count
            19

        Returns: :class:`Folder <pyOutlook.core.folder.Folder>`

def parent_folder(self):
        # type: () -> Folder
        """ Returns the :class:`Folder <pyOutlook.core.folder.Folder>` this message is in

            >>> account = OutlookAccount('')
            >>> message = account.get_messages()[0]
            >>> message.parent_folder
            Inbox
            >>> message.parent_folder.unread_count
            19

        Returns: :class:`Folder <pyOutlook.core.folder.Folder>`

        """
        if self.__parent_folder is None:
            self.__parent_folder = self.account.get_folder_by_id(self.__parent_folder_id)

        return self.__parent_folder