[Turtle] Help with my Mining code

local function refuel()

-- refuel: checks the fuel level, if it is not unlimited or if there is fuel/power left it does nothing, otherwise it selects slot one and refuels from it

local fuelLevel = turtle.getFuelLevel()
if fuelLevel ~= "unlimited" or fuelLevel > 0 then
turtle.select(1)
turtle.refuel(1)
end
end

local function twoByOne()
--the actually digging for the turtle
while turtle.detect()==true do
  turtle.dig()
  if turtle.detect()~=true then
        turtle.forward()
        sleep(0.5)
  end
while turtle.detectUp()==true do
  turtle.digUp()
  if turtle.detectUp()~=true then
  end
end
--##CREDIT TO mikey53591 ON THE CC FORUMS## This tells the turtle to keep digging until there are no blocks detected then ends the cycle--

-- asks the user for the distance to dig

print "How far forward? "
y = io.read()
y = tonumber(y)
i = 1

for i = 1, y, 1 do

-- torch placer

if i%7 == 0 then
turtle.select(2)
turtle.placeUp()
end

-- main loop that runs the functions until the distance required is meet

refuel()
sleep(0.25)

twoByOne()
sleep(0.25)

end

if not fuelLevel == "unlimited" or fuelLevel > 0 then

if fuelLevel ~= "unlimited" or fuelLevel > 0 then

local function twoByOne()
--the actually digging for the turtle
turtle.dig()
sleep(0.5)
forward()
turtle.digUp()
end

local function twoByOne()
--the actually digging for the turtle
while turtle.detect()==true do
  turtle.dig()
  if turtle.detect()~=true then
	turtle.forward()
	sleep(0.5)
  end
while turtle.detectUp()==true do
  turtle.digUp()
  if turtle.detectUp()~=true then
  end
end
--This tells the turtle to keep digging until there are no blocks detected then ends the cycle--