def get_available_routes(availability):
    """
    return all available routes from an availability matrix
    """
    routes = []
    v = len(availability)
    c = len(availability[0][0])
    for i in range(v):
        for j in range(v):
            for k in range(c):
                if availability[i][j][k] == 1:
                    routes.append(((i,j,k)))
    return routes