What is the purpose of the two colons in this Python string-slicing statement?
python, slice
Solution
in sequences' description:
s[i:j:k] slice of s from i to j with step k
The slice of `s` from `i` to `j` with step `k` is defined as the sequence of items with index `x = i + n*k` such that `0 <= n < (j-i)/k`. In other words, the indices are `i`, `i+k`, `i+2*k`, `i+3*k` and so on, stopping when `j` is reached (but never including `j`). If `i` or `j` is greater than `len(s)`, use `len(s`). If `i` or `j` are omitted or `None`, they become “end” values (which end depends on the sign of `k`). Note, `k` cannot be zero. If `k` is `None`, it is treated like 1.
Problem
For example, ``` str = "hello" str[1::3] ``` And where can I find this in Python documentation?