## Letter Space Number

### Instructions

Make a function called `letterSpaceNumber` that receives a string and returns an
array with every instance of a letter, followed by a space, followed by a number
only if that number has only one digit and is not followed by any letter.

### Notions

- [github.com/ziishaned/learn-regex#3-shorthand-character-sets](https://github.com/ziishaned/learn-regex#3-shorthand-character-sets)