def get_organism_screenids(session, organism, idr_base_url=
    'https://idr.openmicroscopy.org'):
    """
    Return a list of screen ids in IDR
    for given case insensitive organism. (Uses the json api)
    """
    screen_id_list = []
    qs = {'base': idr_base_url, 'key': 'organism', 'value': organism}
    screens_projects_url = '{base}/mapr/api/{key}/?value={value}'
    url = screens_projects_url.format(**qs)
    sr = session.get(url)
    sr.raise_for_status()
    for s in sr.json()['screens']:
        screen_id_list.append(str(s['id']))
    return screen_id_list
