def _explode_by_concat(df_in, column, agg_by: str = " "):
    """
    "shreds" the given field of the dataframe, by concatennating all elements of the given list of strings
    This is as compared with the "horizontal explode method, which separates out each element into its own column
    does not change the name of the column, simply replaces each list with the concatted form of itself.
    In some cases this may be a much more idiomatic way to deal with multilevel headers.
    :param df_in: the df to operate on
    :param column: the column in ``df_in`` to operate on
    :param agg_by: The character to place in between elements of the list. defaults to " " but can be set otherwise
    :return: the modified dataframe
    """

    def agg_horiz_headers(series):
        series[column] = agg_by.join(series[column])
        return series

    df = df_in.copy()
    df = df.apply(agg_horiz_headers, axis=1)
    return df, [column]