Newbie: The philosophy behind list indexes

[ian.l.cameron at gmail.com]

I bet this is asked quite frequently, however after quite a few hours searching I haven't found an answer.

What is the thinking behind stopping 'one short' when slicing or iterating through lists?

By example;

>>> a=[0,1,2,3,4,5,6]
>>> a
[0, 1, 2, 3, 4, 5, 6]
>>> a[2:5]
[2, 3, 4]

To my mind, it makes more sense to go to 5. I'm sure there's a good reason, but I'm worried it will result in a lot of 'one-off' errors for me, so I need to get my head around the philosophy of this behaviour, and where else it is observed (or not observed.)

I'm just a hobbyist who likes to learn things, and the Raspberry Pi has me interested in Python. I have dabbled in QB, VB, Spin (Parallex), Bascom, and Arduino's in the past.

Thanks for your insights!

Ian.