Useless PDF writing | Python Fiddle

import requests
import re
from pprint import pprint

# Globals
url = 'http://pages.cs.wisc.edu/~remzi/OSTEP/'

def write_nums(file, start, end, num_to_suffix):
    """
    Start & end are inclusive
    """
    for i in range(start, end + 1):
        pdf_url = url + num_to_suffix[i]
        r = requests.get(pdf_url)
        file.write(r.content)

def write_urls(file, urls):
    for suffix in urls:
        pdf_url = url + suffix
        r = requests.get(pdf_url)
        file.write(r.content)

def main():
    r = requests.get(url)
    
    rows = [line for line in r.text.split('\n') if line.find('.pdf') > 0]
    book_num = 0
    num_to_suffix = dict()
    firsts = []
    appendices_suffixes = []

# Book files
    intro = open('intro.pdf', 'ab+')
    virtualization = open('virtualization.pdf', 'ab+')
    concurrency = open('concurrency.pdf', 'ab+')
    persistence = open('persistence.pdf', 'ab+')
    appendices = open('appendices.pdf', 'ab+')
    files = [intro, virtualization, concurrency, persistence, appendices]

for row in rows:
        match = re.match(r'.+<small>(\d+).+?href=(\S+)', row)
        link = re.match('.+?href=(\S+)', row)

if match:
            num = int(match.group(1))
            suffix = str(match.group(2))
            num_to_suffix[num] = suffix
        elif link:
            link = str(link.group(1))
            if link.find('preface') > -1 or link.find('toc') > -1:
                firsts.append(link)
            else:
                appendices_suffixes.append(link)

# Intro (has preface & TOC)
    write_urls(intro, firsts)
    write_nums(intro, 1, 2, num_to_suffix)

# Virtualization
    write_nums(virtualization, 3, 24, num_to_suffix)

# Concurrency
    write_nums(concurrency, 25, 34, num_to_suffix)

# Persistence
    write_nums(persistence, 35, 50, num_to_suffix)

# Appendices
    write_urls(appendices, appendices_suffixes)

# Close files
    for file in files:
        file.close()

if __name__ == '__main__':
    main()

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