def rivers_with_station(stations):
    """Returns a container of river names with stations, without any duplicating entries"""

    # Initialise a list
    list_of_rivers = []

    # First create a list of all the rivers associated with each station 
    for station in stations:
        list_of_rivers.append(station.river)
    
    set_of_rivers = set(list_of_rivers)

    return set_of_rivers