I need to find the unique last names from a .txt file that looks like this:

```
Kent, Mackenna -- ut
    Voluptatem ipsam et at.
Marven, Gardens -- non
    Facere et necessitatibus animi.
McLaughlinn, Matt -- consequatur
    Eveniet temporibus ducimus amet eaque.
Lang, August -- pariatur
    Unde voluptas sit fugit.
Brad, Nick -- et
    Maiores ab officia sed.
Adam, Levine -- error
    Repellendus alias officia amet et perspiciatis.
Learner, York -- nesciunt
    Incidunt et ut necessitatibus porro.
Ortiz, Andrew -- fuga
    Tempore eos et hic.
Lang, Bryant -- et
Laborum perferendis inventore eveniet.

```

So far I have:

```
FNAME = 'example.txt'

# maps for last name in file
def last_name_from_file(file_name)
  last_name = File.readlines(file_name).reject(&:empty?)
  last_name.map do |line|
    line.split.first
  end
end
puts last_name_from_file('example.txt')

```

but this gives me the output which includes the Lorem text and the last name.

```
#Kent
#Voluptatem
#Marven
#Facere
#McLaughlinn
#Eveniet
#Lang
#Unde
#Brad
...

```