Implement a function sum(num) that sums numbers by accepting a number and allows for repeated calling with more numbers until it is called without arguments.

The function should:

• Accept a number and return a function that continues accumulating the sum.
• When called without arguments, return the total sum.

Examples

sum(1)(2)(3)(); // 6
sum(10)(20)(30)(40)(); // 100
sum(5)(); // 5