Get the parent folder from attribute self.parent or
        getting it from the cloud

        :return: Parent Folder
        :rtype: mailbox.Folder or None

def get_parent_folder(self):
        """ Get the parent folder from attribute self.parent or
        getting it from the cloud

        :return: Parent Folder
        :rtype: mailbox.Folder or None
        """
        if self.root:
            return None
        if self.parent:
            return self.parent

        if self.parent_id:
            self.parent = self.get_folder(folder_id=self.parent_id)
        return self.parent