def outlier_removal_null(dataframe, colname, low_cut, high_cut):
    """Replace outliers with empty values on dataframe[colname]"""
    col = dataframe[colname]
    dataframe.loc[col.apply(lambda x: isinstance(x, (int, float)) and (x <
        low_cut or x > high_cut)), colname] = None
    return dataframe
