<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _parent_info(self):
 """Get fully-qualified parent path and prefix for this collection. Returns: Tuple[str, str]: Pair of * the fully-qualified (with database and project) path to the parent of this collection (will either be the database path or a document path). * the prefix to a document in this collection. """

        parent_doc = self.parent
        if parent_doc is None:
            parent_path = _helpers.DOCUMENT_PATH_DELIMITER.join(
                (self._client._database_string, "documents")
            )
        else:
            parent_path = parent_doc._document_path

        expected_prefix = _helpers.DOCUMENT_PATH_DELIMITER.join((parent_path, self.id))
        return parent_path, expected_prefix