sample extension, create sample! method

array.rb

class Array
  def sample!(n = nil)
    raise TypeError.new('no implicit conversion of String into Integer')  unless n.class == Integer
    new_array = self.clone
    random_sample =  n.nil? ? sample : sample(n)
    new_array -= random_sample.class == Array ? random_sample : [random_sample]
    replace(new_array)
    random_sample
  end
end