from functools import wraps

def ensure_fewer_than_three_args(fn):
    @wraps(fn)
    def wrapper(*args, **kwargs):
        if len(args) < 3:
            return fn(*args, **kwargs)
        return "Too many arguments!"
    return wrapper

@ensure_fewer_than_three_args
def add_all(*nums):
    return sum(nums)

print(add_all())
print(add_all(1))
print(add_all(1,2))
print(add_all(1,2,3))
print(add_all(1,2,3,4,5,6))