When you `zip()`

together three lists containing 20 elements each, the result has twenty elements. Each element is a three-tuple.

See for yourself:

```
In [1]: a = b = c = range(20)
In [2]: zip(a, b, c)
Out[2]:
[(0, 0, 0),
(1, 1, 1),
...
(17, 17, 17),
(18, 18, 18),
(19, 19, 19)]
```

To find out how many elements each tuple contains, you could examine the length of the first element:

```
In [3]: result = zip(a, b, c)
In [4]: len(result[0])
Out[4]: 3
```

Of course, this won’t work if the lists were empty to start with.