functional-options: New() function returns a value of the wrong type

[itsMohammadHeidari]

I think in the functional-option.md in the Constructor section, the type of the New() function returned values ​​is different from the type required in the function signature.
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[cassamajor]

os.Chown returns an error.

The constructor returns os.Chown.

Therefore the constructor returns an error.

[snamiki1212]

Same here. It seems file.New in Usage returns (file, err) but New in Constructor returns only error so this might cause misunderstanding.