def has_station(train, look_for_station):
    """Check if this `train` stops at the given station (by the station name).
    Returns the index of this station within train["stations"], or
    if the train does not stop returns -1.
    """
    for idx, stoptime in enumerate(train["stations"]):
        if stoptime["sta"] == look_for_station:
            return idx
    return -1