dragon

p = peripheral.wrap("back")
local mobs

while true do
  mobs = p.getEntityIds("mob")
  if (table.getn(mobs) == 0) then
  rs.setAnalogOutput("bottom", 0)
  end

  for k,v in pairs(mobs) do
    local dragon = (p.getEntityData(v,"mob").basic().name)
    print (dragon)
    if (dragon) == "Ender Dragon" then
    rs.setAnalogOutput("bottom", 15)
    else
    rs.setAnalogOutput("bottom", 0)
    end
  end
  os.sleep(10)
end