gh-123658 Added a built-in average function

[zykron1]

Added a built-in average function

gh-123658: Added a builtin average function

This pull request is based on #123658. I would like to propose that we add a builtin average function. I am aware this is potentially controversial and thus is probably not getting merged.

Benchmarking

I ran a benchmark on the following hardware:
iMac (Retina 4K, 21.5-inch, 2019)
3.6 GHz Quad-Core Intel Core i3
8 GB 2400 MHz DDR4
Radeon Pro 555X 2 GB

>>> from random import randint
>>> from statistics import mean
>>> from functools import wraps
>>> def timer(func):
...     @wraps(func)
...     def wrapper(*args, **kwargs):
...         start_time = time.time()
...         result = func(*args, **kwargs)
...         end_time = time.time()
...         duration = end_time - start_time
...         print(f"Function '{func.__name__}' took {duration:.4f} seconds to complete.")
...         return result
...     return wrapper
...     
>>> l = []
>>> for _ in range(1_000_000):
...     l.append(randint(-1_000_000, 1_000_000))
...     
>>> @timer
... def smean():
...     return mean(l)
...     
>>> @timer
... def bmean():
...     return avg(l)
...     
>>> bmean_result = bmean()
Function 'bmean' took 0.1531 seconds to complete.
>>> smean_result = smean()
Function 'smean' took 1.9991 seconds to complete.
>>> bmean_result == smean_result
True

As you can see, the new code is already faster than the current solution in the python standard library.

[ghost]

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[hugovk]

Please see #123658 (comment).