code: function average(array) {
    var length = array.length;
  
    if (length === 0) {
      throw new RangeError("Error");
    }
  
    var index = -1;
    var result = 0;
  
    while (++index < length) {
      result += array[index];
    }
  
    return result / length;
  }
docs: Returns the average of the numbers in `array`.
  
  @param {Array} array Range of numbers to get the average.
  @return {number}
  @example
  
  average([100, -100, 150, -50, 100, 250]);
  // => 75