The values arrive as tuple.

examples/functions/sum.py
from __future__ import print_function

def sum(*numbers):
    print(numbers)
    sum = 0
    for s in numbers:
        sum += s
    return sum

print(sum(1))
print(sum(1, 2))
print(sum(1, 1, 1))
examples/functions/sum.py.out
(1,)
1
(1, 2)
3
(1, 1, 1)
3

The 'numbers' argument is a tuple.