Index procedure | Python Fiddle

# Define a procedure, add_to_index,
# that takes 3 inputs:

# - an index: [[<keyword>,[<url>,...]],...]
# - a keyword: String
# - a url: String

# If the keyword is already
# in the index, add the url
# to the list of urls associated
# with that keyword.

# If the keyword is not in the index,
# add an entry to the index: [keyword,[url]]

def add_to_index(index, keyword, url):
    for entry in index:
        if entry[0] == keyword:
            entry[1].append(url)
            return
    index.append([keyword, [url]])

def lookup(index, keyword):
    for entry in index:
        if entry[0] == keyword:
            return entry[1]
    return []

def add_page_to_index(index, url, content):
    words = content.split()
    for word in words:
        add_to_index(index, word, url)

add_to_index(index,'udacity','http://udacity.com')
add_to_index(index,'computing','http://acm.org')
add_to_index(index,'udacity','http://npr.org')
print index
#>>> [['udacity', ['http://udacity.com', 'http://npr.org']], 
#>>> ['computing', ['http://acm.org']]]

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