get the links.py

def get_next_target(page):
    start_link = page.find('<a href=')

    # if the link tag sequence is not found, find returns a -1
    if start_link == -1:
        # return the error codes of None, 0 now and skip the rest!
        return None, 0

    start_quote = page.find('"', start_link)
    end_quote = page.find('"', start_quote + 1)
    url = page[start_quote + 1:end_quote]
    return url, end_quote



def print_all_links(page):
    while True:
        url, endpos = get_next_target(page)
        if url:
            print (url)
            page = page[endpos:]
        else:
            break

print_all_links('https://automatetheboringstuff.com/appendixb/')