concat multiple arrays

hi,
joining multiple arrays is easy using "+"

we can do that using a single method as follows,

class Array
  def concat_multi *lists
    lists.each {|list| self.concat(list) }
  end
end

a = [1, 2, 3]
b = [4, 5, 6]
c = [7, 8, 9]
d = [10, 11]

a.concat_multi(b, c, d)
p a