bucketSlot = 1
lavaSlot = 2
while (true) do
    if ((turtle.getItemCount(bucketSlot) > 1) and (turtle.getItemCount(lavaSlot) > 1)) then
        turtle.select(lavaSlot)
        turtle.place()
        turtle.select(bucketSlot)
        turtle.place()
    end
    sleep(0.5)
end