def select_from_arxivcs_mag(sconn, scur, paper_id):
    """ Queries the sqlite3 table unpaywall on paper_id, returns the pdf_url (can be None)"""
    # cur = conn.cursor()
    query = """
    SELECT pdf_url 
    FROM arxivcs_mag WHERE paper_id = '{}' 
    """.format(paper_id)
    scur.execute(query)
    # Only get one row (there will only be 1 row in the result). Only 1 field present.
    return scur.fetchone()[0]