# sum_13





Return the sum of the numbers in the list, returning 0 for an empty list. Except the number 13 is very unlucky, so it does not count and numbers that come immediately after a 13 also do not count.

This exercise was taken from [codingbat.com](https://codingbat.com/prob/p127384) and has been adapted for the Python language. There are many great programming exercises there, but the majority are created for Java.






### Test 1
**Input:**
```
[1, 2, 2, 1]
```
**Output:**
```
6
```
### Test 2
**Input:**
```
[1, 1]
```
**Output:**
```
2
```
### Test 3
**Input:**
```
[1, 2, 2, 1, 13]
```
**Output:**
```
6
```
### Test 4
**Input:**
```
[1, 2, 13, 2, 1, 13]
```
**Output:**
```
4
```
### Test 5
**Input:**
```
[13, 1, 2, 13, 2, 1, 13]
```
**Output:**
```
3
```
### Test 6
**Input:**
```
[]
```
**Output:**
```
0
```
### Test 7
**Input:**
```
[13]
```
**Output:**
```
0
```
### Test 8
**Input:**
```
[13, 13]
```
**Output:**
```
0
```
### Test 9
**Input:**
```
[13, 0, 13]
```
**Output:**
```
0
```
### Test 10
**Input:**
```
[13, 1, 13]
```
**Output:**
```
0
```
### Test 11
**Input:**
```
[5, 7, 2]
```
**Output:**
```
14
```
### Test 12
**Input:**
```
[5, 13, 2]
```
**Output:**
```
5
```
### Test 13
**Input:**
```
[0]
```
**Output:**
```
0
```
### Test 14
**Input:**
```
[13, 0]
```
**Output:**
```
0
```