def add_query(df, name, past_queries):
    """
    Append a dataframe object, with associated name to a query_dictionary.
    A query_dictionary is intended to save the result of every query as
    a dataframe object that is callable via it's key. The keys in the
    dictionary can then be passed to ipywidgets as a list of strings for
    dropdown menu.
    Keyword arguments:
    df : pandas.DataFrame
        The dataframe to save
    name: string
        a string describing the DataFrame
    past_queries : dictionary
        A dictionary to append to in the form of
        key:value :: dataframe_id:dataframe
    Returns:
    -------
    past_queries : dictionary
        A dictionary in the form of key:value :: dataframe_id:dataframe
    """
    past_queries[name] = df
    return past_queries