code: def parent(self) -> Span | None:
      if self._parent:
          out = self._parent()
          assert out
          return out
      return None
  
imports: from __future__ import annotations
  import uuid
  import weakref
  from collections import defaultdict
  from collections.abc import Hashable, Iterable, Iterator
  from contextlib import contextmanager
  from itertools import islice
  from typing import TYPE_CHECKING, Any
  import dask.config
  from dask.typing import Key
  from distributed.collections import sum_mappings
  from distributed.itertools import ffill
  from distributed.metrics import time
label_desc: Use image node_id 3 for calling the Span obj's underlying member method code with example usage: obj.parent() and returns: None, out