Calculate differences between elements of a sequence in Python

I often encounter the need to calculate the (finite) differences between elements of a sequence, e.g., to calculate the duration between points in a time-series.

The calculation is simple, for the sequence [a,b,c,d] the difference between the elements are [b-a,c-b,d-c].

Hence, for the sequence [1,2,3,5,6,9], the differences between the elements are: [1,1,2,1,3].

The function is built-in to most high-level languages used for technical computing, such as Matlab and Julia.

To the best of my knowledge, Python doesn't have a built in way to perform this calculation.

Here's the function I've created, implementing the diff algorithm in Python, using tee from the built-in itertools module:

from itertools import tee

def diff(s):
    """Diff elements of a sequence:
    s -> s1 - s0, s2 - s1, s3 - s2, ...
    a, b = tee(s)
    next(b, None)
    return (j - i for i, j in zip(a, b))

This works fine, but maybe there is a more compact, and elegant way to do it.