The "readLux" function of the code is supposed to execute the function as part of the TSL2561 class. (Be real careful reading too much in to what I'm saying here, I'm just barely putting this stuff in to practice. You can already see the screw-up and learning experience I've already provided).
Inside of a Class, the first variable passed to a function (the first item inside the parentheses) is traditionally (Pythonically) "self". In reality it doesn't matter what the first thing is actually called (I think it needs to be consistent throughout the class). By Python convention it is "self".
If I understand it correctly, "self" allows the function to refer to the class variables that house the class functions.
There are some pretty good books out there (I know, I know, more reading). I pulled Mark Pilgrim's book down "Dive into Python 3", and it looks pretty good. The only issue is that Classes are chapter 7. He does a great job of building on his previous examples. The book is good, but you kinda have to start from chapter 1.
http://getpython3.com/diveintopython3/
However, it appears to be free, online (Mr. Pilgrim, I'll buy you a beer if I ever meet you. At least one).
There are other books that will let you just jump into Classes and Objects, but I haven't seen one that just "conveys it". This is one of the areas where Python is incredibly powerful. You need to work at it, but once you get it, it mostly clicks (says the pure amateur, me).
I've run in to the "out of stock notice" from Adafruit. I also got my shipment on time, somehow, in the aftermath of Sandy. That impressed me (I'm an emergency response guy, by trade).
The big thing that does it for me is this board and the technical support. Yeah, I pay a little bit more for things from here. I'll be the first to admit that sometimes I have to buy elsewhere, or find alternate means of procurement (I kit bash and hack things together, that's part of what we do). But these folks do an incredible job. I tried playing with this stuff for decades, and just wasn't getting it. A little willingness to fail (Blowing $30 worth of parts hurts, but isn't damaging), a lot of willingness to read and learn, and some quiet encouragement from the staff here has worked miracles.
Then coming on to the board here and writing things out has really impressed me. You folks are building really cool....stuff (ok, I'm not allowed to use certain words? Words I say to my students or in front of someone else's mother?). Some of those things are utterly inane (why do you do it? Because it's there). Others are building gadgets that would cost hundreds to thousands of dollars (I'm looked for exotic monitoring equipment when I was writing my undergraduate thesis). You're critically thinking, getting a little uncomfortable, and doing really cool things. Some of these things are probably out of your realm, and that's just so freakin' awesome.
I'm kinda jealous of these projects, but really glad you're writing about them.

