pythonize this!

[superpollo]

Peter Otten ha scritto:
> superpollo wrote:
> 
>> goal (from e.c.m.): evaluate
>> 1^2+2^2+3^2-4^2-5^2+6^2+7^2+8^2-9^2-10^2+...-2010^2, where each three
>> consecutive + must be followed by two - (^ meaning ** in this context)
> 
>>>> from itertools import cycle, izip
>>>> sum(sign*i*i for sign, i in izip(cycle([1]*3+[-1]*2), range(1, 2011)))
> 536926141

don't understand it bit i like this a lot!