/// A duration between two `MonthlyDates`. The value can be positive or negative.

/// A duration between two `MonthlyDates`.
///
/// The value can be positive or negative.

/// A date with granularity of one month or larger. Dates can also act as durations and be added
/// and subtracted.

/// A date with monthly granularity or larger.

/// To avoid pulling in redundant dependences, the responsibility for parsing a date in string form
/// is left to the client code.

/// Client code is responsible for parsing strings into `MonthlyDate`s.

/// A date of monthly granularity associated with a numeric array of data.

/// A `MonthlyDate` associated with some data.

/// `TimeSeries` is a collection of `DatePoints`. There are no guarantees of ordering.

/// A time-series with no guarantees of ordering.

            .map_err(|_| failed_to_read_file(file!(), line!(), &path))?;

            .map_err(|_| read_file_error(file!(), line!(), &path))?;

                    return Err(failed_to_parse_csv_date(

                    return Err(parse_csv_date_failed(

                    return Err(failed_to_parse_csv_date(

                    return Err(parse_csv_date_failed(

                    return Err(failed_to_parse_csv_value(

                    return Err(parse_csv_value_failed(

/// A `RegularTimeSeries` has an additional requirements over `TimeSeries` in the time interval
/// between successive `DatePoints` has the same `Duration`.  This also ensures ordering. A
/// `RegularTimeSeries` is guaranteed to have two or more data points.

/// A time-series with regular, contiguous data.
///
/// A `RegularTimeSeries` is guaranteed to have two or more data points.

// Constrain a `RegularTimeSeries` in-place with a new date range.

    pub fn with_range(&mut self, date_range: &DateRange) {

    pub fn mut_range(&mut self, date_range: &DateRange) {

    }
}
// Return a new `RegularTimeSeries` with a new date range.
impl<const N: usize> RegularTimeSeries<N> {
    /// Remove `DatePoints` outside `date_range` from `Self`.
    pub fn range(&self, date_range: &DateRange) -> RegularTimeSeries<N> {
        let start_date = match date_range.start_date {
            None => self.ts.0.first().unwrap().date(),
            Some(start) => start,
        };
        let end_date = match date_range.end_date {
            None => self.ts.0.last().unwrap().date(),
            Some(end) => end,
        };
        let mut ts = TimeSeries::new(Vec::new());
        for dp in self.ts.0.iter() {
            if dp.date() >= start_date && dp.date() <= end_date {
                ts.0.push(*dp)
            };
        }
        ts.try_into().unwrap()

/// A `DateRange` is used to constrain a `TimeSeries` iterator over a range of dates. If
/// `start_date` or `end_date` are `None` then the iterator will start at the first value in the
/// `TimeSeries` or end at the last value in the `TimeSeries` respectively.
#[derive(Clone, Copy, Debug)]

/// Specifies the time-span of the data.
#[derive(Clone, Copy, Debug, Serialize)]

        "[time_series:01:{}:{}] Expected positive duration between {} and {}.",

        "[time_series:02:{}:{}] Expected positive duration between {} and {}.",

        "[time_series:01] Expected regular time-series."

        "[time_series:03] Expected regular time-series."

pub fn failed_to_parse_csv_date(

pub fn parse_csv_date_failed(

        "[time_series:02:{}:{}] Line: {} file: {}, . Failed to parse date on line [{}].",

        "[time_series:04:{}:{}] Line {} file {}. Failed to parse date on line [{}].",

pub fn failed_to_parse_csv_value(

pub fn parse_csv_value_failed(

        "[time_series:03:{}:{}] Line: {} file: {}. Failed to parse value on line [{}].",

        "[time_series:05:{}:{}] Line {} file {}. Failed to parse value on line [{}].",

pub fn failed_to_read_file(

pub fn read_file_error(

        "[time_series:05:{}:{}] Failed to read file [{}].",

        "[time_series:06:{}:{}] Failed to read file [{}].",

        "[time_series:04:{}:{}] Time-series has only one point.",

        "[time_series:07:{}:{}] Time-series has only one point.",

        "[time_series:05:{}:{}] Time-series is empty.",

        "[time_series:08:{}:{}] Time-series is empty.",