Why have I been told to bring a story to a job interview?

Hi, thanks for looking. I've got a job interview soonish for a position at a library. I have been told to bring a story with me to read but i was wondering if anyone has any idea why this would be? I was thinking it could be just to see if i am literate enough for the job but why would that mean i would have to take something with me, couldnt they just give me something to read? Im just a bit confused and im not really sure what to take, i mean they did say any kind of story but that depends on their definition of story. Looking at the definition in a dictionary says it could mean i could take a novel or it could also mean they are expecting something a lot shorter than a novel. I was thinking Frankenstein as thats one of my favourite novels but dont know if that would be suitable. Any ideas? Thanks for any help.