[1::2,::2] in python code example

Example 1: string slicing in python 3 arguments

#[start:end:step]
>>> range(10)[::2]
[0, 2, 4, 6, 8]

Example 2: [1::2] python

>>> L = range(10)
>>> L[::2]
[0, 2, 4, 6, 8]