Dump :class:`mongomock.database.Database` to dict data.

def _dump(db):
    """
    Dump :class:`mongomock.database.Database` to dict data.
    """
    db_data = {"name": db.name, "_collections": dict()}

    for col_name, collection in iteritems(db._collections):
        if col_name != "system.indexes":
            col_data = {
                "_documents": collection._documents,
                "_uniques": collection._uniques,
            }
            db_data["_collections"][col_name] = col_data

    return db_data