def _parse_placekey(placekey):
    """
    Split a Placekey in to what and where parts.

    :param placekey: Placekey (string)
    :return: what (string), where (string)

    """
    if '@' in placekey:
        what, where = placekey.split('@')
    else:
        what, where = None, placekey

    return what, where