def extract_keywords(text):
    """ After finding the string "Keywords", each line
    is a keyword until an empty line is found """
    keywords = list()
    reading_keywords = False
    all_lines = text.split('\n')

    for line in all_lines:
        if 'Keywords' in line:
            reading_keywords = True

        # nothing in line
        elif not line and reading_keywords:
            return ','.join(keywords)

        elif reading_keywords:
            keywords.append(line)
    return ','.join(keywords)