array.array isn't a normal python array. It's an optimized type/object where all the elements of the array are of the same type. The 'B' is a format string that indicates what type you want the elements to be. B == unsigned char

He's using it because it converts the int 65 to the string 'A', then toString() to join all the array elements together.

https://docs.python.org/2/library/array.html

See my other post though, it's not the fastest way to do this in python.

The python timings are for 1000 iterations. You are currently comparing apple to 1000 apples :)

`array.array` is more like a C array than a Python list.