code: function flattenDeep(array) {
        var length = array == null ? 0 : array.length;
        return length ? baseFlatten(array, INFINITY) : [];
      }
docs: Recursively flattens `array`.
  
  @static
  @memberOf _
  @since 3.0.0
  @category Array
  @param {Array} array The array to flatten.
  @returns {Array} Returns the new flattened array.
  @example
  
  _.flattenDeep([1, [2, [3, [4]], 5]]);
  // => [1, 2, 3, 4, 5]