List files for an installed package

def list_packages(conn=None):
    '''
    List files for an installed package
    '''
    close = False
    if conn is None:
        close = True
        conn = init()

    ret = []
    data = conn.execute('SELECT package FROM packages')
    for pkg in data.fetchall():
        ret.append(pkg)

    if close:
        conn.close()
    return ret