# Challenge

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## Custom zip

The built-in `zip`

function "zips" two lists. Write your own implementation of
this function.

Define a function named `zap`

. The function takes two parameters, `a`

and `b`

.
These are lists.

Your function should return a list of tuples. Each tuple
should contain one item from the `a`

list and one from `b`

.

You may assume `a`

and `b`

have equal lengths.

If you don't get it, think of a zipper.

For example:

```
zap(
[0, 1, 2, 3],
[5, 6, 7, 8]
)
```

Should return:

```
[(0, 5),
(1, 6),
(2, 7),
(3, 8)]
```

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