I can't seem to get this one

Question:You've seen how random.choice() works. It gets a random member from an iterable (like a list or a string). I want you to try and reproduce it yourself. First, import the random library. Then create a function named random_item that takes a single argument, an iterable. Then use random.randint() to get a random number between 0 and the length of the iterable, minus one. Return the iterable member that's at your random number's index. Check the file for an example.

I used ```import random

def random_item(yes): return yes[random.randint(0,len(yes)-1)]```

But the correct answer was

import random

def random_item(iterable):
  return iterable[random.randint(0,len(iterable)-1)]

Why am I wrong, and what does iterable[] mean specifically?

# EXAMPLE
# random_item("Treehouse")
# The randomly selected number is 4.
# The return value would be "h"