Pythonic Circular List

Question

Say I have a list,

l = [1, 2, 3, 4, 5, 6, 7, 8]

I want to grab the index of an arbitrary element and the values of its neighbors. For examp

Answer 1

a = [2,3,5,7,11,13]

def env (l, n, count):
    from itertools import cycle, islice
    index = l.index(n) + len(l)
    aux = islice (cycle (l), index - count, index + count + 1)
    return list(aux)

Behaves as follows

>>> env (a, 2,1)
[13, 2, 3]
>>> env (a,13,2)
[7, 11, 13, 2, 3]
>>> env (a,7,0)
[7]