If I have a list that looks like this:

```py
['1 184',
 '1 29',
 '1 31',
 '1 12',
 '1 51',
 '1 102',
 '1 13',
 '1 14',
 '1 15',
 '1 57',
 '1 378',
 '1 859',
 '1 185',
 '1 30',
 '1 37',
 '1 52',
 '1 142',
 '1 195',
 '1 875',
 '1 56',
 '1 66',
 '1 95',
 '1 462',
 '1 497',
 '1 858',
 '1 876',
 '1 879',
 '1 880',
 '2 12',
 '2 15',
 '2 184',
 '2 858',
 '2 51']

```

And I wanted to map the first element of each string to each of the next elements tied to that first number, and get it in the format of `{1 : [184, 29, 31...], 2 : [12, 15, 18, ...]}`.

How could I do that?