Downloaded pdf files are corrupt files

After running the script and downloading a file. The output is a corrupt 0 byte file. Tested on Windows 10 and Python 3. Here's the replication code: 

`python pylibgen.py python web scraping`

`Type # of book to download or q to quit: 2`

`Web Scraping with Python: Collecting Data from the Modern Web [1 ed.] 1491910291, 9781491910290.pdf`

