When should I use `return` in es6 Arrow Functions?

Question

The new es6 arrow functions say return is implicit under some circumstances:

The expression is also the implicit return value of that fun

Answer 1

I understand this rule-of-thumb ...

For functions that are effectively transforms (one-line-manipulations of arguments), return is implicit.

Candidates are:

// square-root 
value => Math.sqrt(value)

// sum
(a,b) => a+b

For other operations (more than one-liners that require a block, return has to be explicit