Error with my first turtle program

bios:14: [string "chopWood"]:12: '=' expected

SET_STEP = 5;
point = 1; -- position poiting to
stepDoneFW = 0; -- step done forward
stepDoneUP = 0; -- step done up
choppedNb = 0; -- number of stuff digged
chopped = false;

function chopTree()
	repeat
		turtle.up();
		turtle.dig();
		choppedNb++;
		stepDoneUP++;
	until !(turtle.detect())
	return stepDoneUP;
end

function move(step,direction)
	stepAccomplish = 0;
	for i=0;step do
		if direction == 'front' then
			if !(turtle.detect()) then
				stepAccomplish++;
				turtle.forward();
			else
				return stepAccomplish;
			end
		else
			turtle.back();
		end
	end
	return stepAccomplish + 1;
end

function Main()
	stepDoneFW = move(SET_STEP,'front');
	if (stepDone <= SET_STEP) then
		stepDoneUP = chopTree();
		for goDown = 0,stepDoneUP do
			turtle.down();
		end
	end
  
	move(stepDoneFW,'backward');
	turtle.turnRight();
end

while point != 1 do
		point++;
		if point > 4 then
			point = 1;
		end
		turtle.turnRight();
end
  
repeat
	Main();
until chopped

print("Buddy I found:" .. choppedNb .. " logs.There ya go chumps!");

choppedNb++;

choppedNb = choppedNb + 1;