The *numbers argument can be preceded by any number of regular arguments

examples/functions/super.py
from __future__ import print_function

def sum(op, *numbers):
    print(numbers)
    if op == '+':
      sum = 0 
    elif op == '*':
      sum = 1 
    else:
        raise Exception('invalid operator {}'.format(op))

    for s in numbers:
        if op == '+':
          sum += s
        elif op == '*':
          sum *= s
  
    return sum

print(sum('+', 1))
print(sum('+', 1, 2))
print(sum('+', 1, 1, 1))
print(sum('*', 1, 1, 1))
examples/functions/super.py.out
(1,)
1
(1, 2)
3
(1, 1, 1)
3
(1, 1, 1)
1