obsidian_gen.lua

local rs_side = "back"
while true do
    local block, block_info = turtle.inspect()
    if block_info['name'] == "minecraft:flowing_lava" or block_info['name'] == "minecraft:lava" then
        redstone.setAnalogOutput(rs_side, 15)
    else
        redstone.setAnalogOutput(rs_side, 0)
    end
    sleep(0.5)
end