Ruby 2.4 implements Enumerable#sum

It is a common use case to calculate sum of the elements of an array or valuesfrom a hash. [1, 2, 3, 4] => 10{a: 1, b: 6, c: -3} => 4Active Support already implementsEnumerable#sum > [1, 2, 3, 4].sum #=> 10> {a: 1, b: 6, c: -3}.sum{ |k, v| v**2 } #=> 46> ['foo', 'bar'].sum # concatenation of strings #=> "foobar"> [[1], ['abc'], [6, 'qwe']].sum # concatenation of arrays #=> [1, "abc", 6, "qwe"]Unti