def arbitrary
  yield 1
  yield 2
  yield 3
  yield 4
end

arbitrary { |x| puts x }

myarray = arbitrary
p a -----> [1,2,3,4,5]

def arbitrary(&block)
  values = [1,4]
  if block
    values.each do |v|
      yield v
    end
  else
    values
  end
end

yield v

block.call v