Solution 1

```
def sum_of_numbers_in_list(a_list):
sum = 0
for number in a_list:
sum += number
return sum
```

# Sum of numbers in list

Define a function `sum_of_numbers_in_list`

that receives a list of numbers

`a_list`

of an unknown length and calculates the sum of those numbers using a

for loop. Do not use the sum function.

Examples:

```
>>> sum_of_numbers_in_list([])
0
>>> sum_of_numbers_in_list([4])
4
>>> sum_of_numbers_in_list([2, 3])
5
>>> sum_of_numbers_in_list([2, 3, 4])
9
```