def stretch!(*arys)
      max_size = (arys + [self]).collect { |a| a.length }.max
      self[max_size - 1] = nil unless self.length == max_size
      return self
    end
def stretch!(*arys)
      max_size = (arys + [self]).collect { |a| a.length }.max
      self[max_size - 1] = nil unless self.length == max_size
      return self
    end
Stretch receiver to be the same size as the longest argument Array.  Modifies the receiver in place.

   [1, 2].stretch!([3, 4], [5, 6, 7])  #=> [1, 2, nil]