Exercise: Create a method to pad an array Implement Array#pad and Array#pad!. Each method accepts a minimum size (non-negative integer) and an optional pad value as arguments.  If the array's length is less than the minimum size, Array#pad should return a new array padded with the pad value up to the minimum size.  For example, ruby [1,2,3].pad(5)  should return  [1,2,3,nil,nil] And ruby [1,2,3].pad(5, 'apple')  should return  [1,2,3,'apple', 'apple'] If the minimum size is less than or equal to the length of the array, it should just return the array.  That is, [1,2,3].pad(3) should return [1,2,3].  my_array.pad(0) should always return an array equal to my_array. Array#pad should always return a new object, i.e., it should be non-destructive.  Array#pad! behaves identically to Array#pad except that it modifies the underlying array.