Thx Fabi! :-)

PS, don't get confused by the `a, b = 0, 1` or the `a, b = b, a + b`notations in the `fibonacci()` function! That's a very good remark of yours (well, you didn't explicitly mention it, but I was hoping already somebody would ask me a question about it, because explaining it in-depth inside the article body would have made the Intro episode even longer! ;-)  ).

But let's look at it closely...

* At variable initiation, `a,b = 0,1` could be re-written as:
```
a = 0
b = 1
```

* However, the same thing **cannot** be said about re-writing `a, b = b, a + b` **inside the `while` loop**!
```
a = b
b = a + b
```
... would result in the sequence `[0, 1, 2, 4, 8, 16, 32, 64, 128, 256, 512]`, which is not a Fibonacci sequence (but setting 0 to 1 and then doubling it every iteration).

The expression `a, b = b, a + b` is happening "at the same time", in **parallel** and not **sequentially**.
At the first iteration `a=0` and `b=1`, so in the loop `a` then is set to what `b` **was** and `b` is set to what `a` **was** plus what `b` **was**. 

```
# iteration abbreviated to i
# i(0) => a = 0 and b = 1 
# i(1) => a = 1 and b = 0 + 1 = 1 ... and add 0 to seq [0]
# i(2) => a = 1 and b = 1 + 1 = 2 ... and add 1 to seq [0,1]
# i(3) => a = 2 and b = 1 + 2 = 3 ... and add 1 to seq [0,1,1]
# i(4) => a = 3 and b = 2 + 3 = 5 ... and add 2 to seq [0,1,1,2]
# i(5) => a = 5 and b = 3 + 5 = 8 ... and add 3 to seq [0,1,1,2,3]
# i(6) => a = 8 and b = 5 + 8 = 13 ... and add 5 to seq [0,1,1,2,3,5]
# etc. etc. etc
```

So, we could have re-written, inside the `while` loop `a, b = b, a + b` to:
```
# first "freeze" the current values
a_old = a
b_old = b

# then change a and b
a = b_old
b = a_old + b_old
```

PS: this series is **not** about me demonstrating how great **my Python** is. It's about
-a- showing how cool Python, the language, is, and
-b- developing **your** Python SuperPowers!

So: have fun using Python, my Learn Python Series, and **feel free to ask me questions**! 
@scipio