def check_sink_place_presence(net):
    """
    Check if there is a unique sink place with empty connections

    Parameters
    -------------
    net
        Petri net

    Returns
    -------------
    place
        Unique source place (or None otherwise)
    """
    count_empty_output = 0
    unique_sink = None
    for place in net.places:
        if len(place.out_arcs) == 0:
            count_empty_output = count_empty_output + 1
            unique_sink = place
    if count_empty_output == 1:
        return unique_sink
    return None