Don't used parameter

[YaroslavTER]

Does this a parameter have a sense in this case? Because it looks redundant.

Yes, I promise I've read the Contributions Guidelines (please feel free to remove this line).

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Edition: 1st

Book Title: this & object prototypes

Chapter: 2nd

Section Title: Lexical this

Problem: unused parametr a

function foo() {
    // return an arrow function
    return (a) => {
        // `this` here is lexically adopted from `foo()`
        console.log( this.a );
    };

[getify]

Asked several times before, please search existing issues.