function sum(array) {
      return (array && array.length)
        ? baseSum(array, identity)
        : 0;
    }
Computes the sum of the values in `array`.

@static
@memberOf _
@since 3.4.0
@category Math
@param {Array} array The array to iterate over.
@returns {number} Returns the sum.
@example

_.sum([4, 2, 8, 6]);
// => 20