Add It Up!

This challenge concerns some functionality of the sum method that is easy to overlook.

As we all know, sum([4, 14, 17, 10]) is an alternative way of writing 4 + 14 + 17 + 10.

So far, nothing particularly interesting. However, things get more noteworthy when one recalls that in Python the addition + isn't just used to add numbers.

For example, the code:

[1, 2] + [4] + [9, 8, 6]

... also makes perfect sense. And, as it turns out, this code can be rewritten using sum as:

sum([[1, 2], [4], [9, 8, 6]], [])

Caution: One must include the empty list [] in the code, which tells Python "how to start the sum". More explicitly, the code above secretly computes the sum [] + [1, 2] + [4] + [9, 8, 6]. Thus, if one doesn't include [] then Python will try to start the sum at 0 (e.g. the code sum([[1, 2], [4], [9, 8, 6]]) computes 0 + [1, 2] + [4] + [9, 8, 6]), resulting in a type error.

Additionally, sum can also be used to add lists of tuples.

For example, the sum:

(2, 4, 5) + (6,) + (9, 8, 7)

... can be similarly rewritten as:

sum([(2, 4, 5), (6,), (9, 8, 7)], ())

Goal: Write a function which receives a non-empty list whose elements are either numbers, lists, or tuples and adds them up. Note that in each test all elements will be of the same type so that adding is possible.

Examples

add_it_up([4, 14, 17, 10]) ➞ 45
# 4 + 14 + 17 + 10

add_it_up([[1, 2], [4], [9, 8, 6]]) ➞ [1, 2, 4, 9, 8, 6]
# [1, 2] + [4] + [9, 8, 6]

add_it_up([(2, 4, 5), (6,), (9, 8, 7)]) ➞ (2, 4, 5, 6, 9, 8, 7)
# (2, 4, 5) + (6,) + (9, 8, 7)

Notes

• Notably, though Python also allows us to add strings, such as with the code "addition " + "of " + "strings", this addition can not be performed using sum. If one attempts to run sum(["addition ", "of ", "strings"], "") one obtains an error message explicitly saying that sum does not work with strings, and indicating that one must use the alternative "".join(["addition ", "of ", "strings"]) syntax instead.
• If you are not familiar with tuples, you may be wondering what's the deal with the comma in the tuple (6,) in the third example. As it turns out, this comma is essential for Python to recognize (6,) as a tuple with a single entry, since the code (6) is interpreted as simply denoting the number 6.