mypy [subprocess.Popen]`“Optional[IO[bytes]]”的“None”项没有属性“close”`

如何解决mypy [subprocess.Popen]`“Optional[IO[bytes]]”的“None”项没有属性“close”`

mypy 为 Item "None" of "Optional[IO[bytes]]" has no attribute "close" 行生成以下警告 p1.stdout.close()。如何修复此错误？

#!/usr/bin/env python3

filename = "filename.py"
p1 = subprocess.Popen(["ls","-ln",filename,],stdout=subprocess.PIPE,)
p2 = subprocess.Popen(["awk","{print $1}"],stdin=p1.stdout,stdout=subprocess.PIPE)
p1.stdout.close()  # <== `Item "None" of "Optional[IO[bytes]]" has no 
                   #     attribute "close"`

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close() 是 abstractmethod() 文件中的 typing.py 方法

@abstractmethod
def close(self) -> None:
   pass