function pulse(side) -- function to pulse the designated side of the computer.  Remember to put your side into quotes, to make it a string.
  rs.setOutput(side, true) -- part of the redstone API.
        sleep(1) -- makes the computer wait 1 second.  Note that the number inside is not in quotes as it is a number, not a string.  It is in seconds.
  rs.setOutput(side, false)
end

while (true) do
	for i = 1,4,1
	do
		pulse("top")
	end
	sleep(4)
end