Update article.md | changes under Comma subheading

[errwnd]

Shouldn't "a" be assigned the value of the later operation(3+4) rather than (1+2).

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[errwnd]

let a = 1 + 2, 3 + 4 // (a = 3), 7 Shall we have a code representation like: let a; a =1+2, 3+4; alert(a); // returns 3