#### Sum of Digits

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```def sum_of_digits(n: int) -> int:
"""
Find the sum of digits of a number.
>>> sum_of_digits(12345)
15
>>> sum_of_digits(123)
6
>>> sum_of_digits(-123)
6
>>> sum_of_digits(0)
0
"""
n = abs(n)
res = 0
while n > 0:
res += n % 10
n //= 10
return res

def sum_of_digits_recursion(n: int) -> int:
"""
Find the sum of digits of a number using recursion
>>> sum_of_digits_recursion(12345)
15
>>> sum_of_digits_recursion(123)
6
>>> sum_of_digits_recursion(-123)
6
>>> sum_of_digits_recursion(0)
0
"""
n = abs(n)
return n if n < 10 else n % 10 + sum_of_digits(n // 10)

def sum_of_digits_compact(n: int) -> int:
"""
Find the sum of digits of a number
>>> sum_of_digits_compact(12345)
15
>>> sum_of_digits_compact(123)
6
>>> sum_of_digits_compact(-123)
6
>>> sum_of_digits_compact(0)
0
"""
return sum(int(c) for c in str(abs(n)))

def benchmark() -> None:
"""
Benchmark multiple functions, with three different length int values.
"""
from collections.abc import Callable
from timeit import timeit

def benchmark_a_function(func: Callable, value: int) -> None:
call = f"{func.__name__}({value})"
timing = timeit(f"__main__.{call}", setup="import __main__")
print(f"{call:56} = {func(value)} -- {timing:.4f} seconds")

for value in (262144, 1125899906842624, 1267650600228229401496703205376):
for func in (sum_of_digits, sum_of_digits_recursion, sum_of_digits_compact):
benchmark_a_function(func, value)
print()

if __name__ == "__main__":
import doctest

doctest.testmod()
benchmark()
```