if n < 0 then raise ArgumentError,  end
raise ArgumentError,  if n < 0


unless Process.respond_to?:fork then exit 1 end
exit 1 unless Process.respond_to?:fork


while ary.length > 0 do puts ary.shift end
puts ary.shift while ary.length > 0


until ary.empty? do puts ary.shift end
puts ary.shift until ary.empty?