return a list of all dbs and related collections.
    Return an empty list on error.

def show_dbs():
    """return a list of all dbs and related collections.
    Return an empty list on error.
    """

    l = []
    mc = client_connector()
    if not mc:
        # The client couldn't connect
        return ()

    dbs = mc.database_names()
    for d in dbs:
        dbc = mc[d]
        collections = dbc.collection_names()
        collections = remove_values_from_list(collections, "system.indexes")
        l.append({"name": d, "collections": collections})
    return tuple(l)