Function arg_max_row 

pub fn arg_max_row(
    dataset: &DataSet,
    column: &str,
) -> Option<Option<(usize, Value)>>

Returns None if column is not in the schema. Otherwise [Some(None)] if there is no non-null comparable value, or [Some(Some((row_index, value)))] for the first row attaining the maximum (stable tie-break).