line in file:lines()

Okay. I made a program in 1.5.2 of Minecraft that used

for line in file:lines() do -- file was already declared

and it worked perfectly. Now I'm trying to get that to work in 1.6.4 using CC1.57, and I get the same error everytime:

attempt to call nil

What am I doing wrong?

EDIT: I found the problem. Apparently the lines() function is removed from the FS API. I have to use IO instead.

Please post the whole code.

Note that ":lines()" is only available to files opened with io.open(), as opposed to fs.open().

Edit: Aaand then his edit comes through.