Python is the only available language which supports negative indexing, so that'd introduce an incosistency, and invalidate all the solutions.

thanks for the Kata.

You may want to consider changing the input from "a" to "s" since it's a string....other than that nice Kata.... :)

lol..it's called multitasking and not paying close attention but solving on auto-pilot...kata upvoted :)

Thanks ;-)
I added this to the description:

Note: The result should be a boolean value, instead of a string.

Nice one!