Thank you for your reply. I did try to modify your code to:
from bs4 import BeautifulSoup

html = open('http://endic.naver.com/search.nhn?isOnlyViewEE=N&query=Rule')
soup = BeautifulSoup(html)
mp3_url = soup.find('a', 'play3')['playlist']
print mp3_url

but didn't work because open is only for files?

I did however find some other code that does work:

import urllib2
from bs4 import BeautifulSoup

url = 'http://endic.naver.com/search.nhn?isOnlyViewEE=N&query=Rule'
page = urllib2.urlopen(url)
soup = BeautifulSoup(page)

playlists = soup.find_all("a", {"playlist": True})
print playlists

print playlists[0].get("playlist")

The only problem now is when I insert it into my main program, it doesn't
work!! Ahhhhhhhhhhhh