for example:
```
from typing import Union
class FakePath:
def __init__(self, path):
self.path = path
def __fspath__(self) -> Union[str, bytes]:
return self.path
if __name__ == "__main__":
from tempfile import TemporaryDirectory
# You need to create `existing_path` directory
with TemporaryDirectory(dir=FakePath("existing_path")) as str_path:
print(str_path) # 'existing_path/...'
with TemporaryDirectory(dir=FakePath(b"existing_path")) as byte_path:
print(byte_path) # expected b'existing_path/...' but raised TypeError
```