I think using 'plusAssign' kotlin operate is better, because call ' a += b ' the user will understand that plus operate may change value of a, but 'c = a + b' may lead to misunderstand that c is a new value, so I implement the 'plusAssign' instead of previous 'plus' operate
I think using 'plusAssign' kotlin operate is better, because call ' a += b ' the user will understand that plus operate may change value of a, but 'c = a + b' may lead to misunderstand that c is a new value, so I implement the 'plusAssign' instead of previous 'plus' operate