Simple vein miner (CC Turtle)

function isFiller(block)
    return block.name == "minecraft:diorite" or block.name == "minecraft:deepslate" or block.name == "minecraft:stone" or block.name == "minecraft:granite" or block.name == "minecraft:cob blestone" or block.name == "minecraft:cobbled_deepslate" or block.name == "minecraft:netherrack" or block.name == "minecraft:grass_block" or block.name == "minecraft:dirt" or block.name == "minecraft:water" or block.name == "minecraft:lava" or block.name == "minecraft:sand" or block.name == "minecraft:farmland" or block.name == "minecraft:chest" or block.name == "minecraft:shulker_box"
end

function checkBlock(direction)
    if direction == 0 then
        local isBlock, block = turtle.inspectDown();
        if isBlock and not isFiller(block) then
            turtle.digDown()
            turtle.down()
            search()
            turtle.up()
        end
    elseif direction == 1 then
        local isBlock, block = turtle.inspect();
        if isBlock and not isFiller(block) then
            turtle.dig()
            turtle.forward()
            search()
            turtle.back()
        end
    elseif direction == 2 then
        local isBlock, block = turtle.inspectUp();
        if isBlock and not isFiller(block) then
            turtle.digUp()
            turtle.up()
            search()
            turtle.down()
        end
    end
end

function search()
    checkBlock(2)
    checkBlock(1)
    turtle.turnLeft()
    checkBlock(1)
    turtle.turnLeft()
    checkBlock(1)
    turtle.turnLeft()
    checkBlock(1)
    turtle.turnLeft()
    checkBlock(0)
end

search()