code: function calculateRegionIndices(
    regionMapping,
    time,
    failedMatches,
    ambiguousMatches
  ) {
    // As described in load, currently we only use the first possible region column.
    var regionDetail = regionMapping._regionDetails[0];
    var tableStructure = regionMapping._tableStructure;
    var regionColumn = tableStructure.getColumnWithNameIdOrIndex(
      regionDetail.columnName
    );
    if (!defined(regionColumn)) {
      return;
    }
    var regionColumnValues = regionColumn.values;
    // Wipe out the region names from the rows that do not apply at this time, if there is a time column.
    var timeColumn = tableStructure.activeTimeColumn;
    var disambigColumn = defined(regionDetail.disambigColumnName)
      ? tableStructure.getColumnWithNameIdOrIndex(regionDetail.disambigColumnName)
      : undefined;
    // regionIndices will be an array the same length as regionProvider.regions, giving the index of each region into the table.
    var regionIndices = regionDetail.regionProvider.mapRegionsToIndicesInto(
      regionColumnValues,
      disambigColumn && disambigColumn.values,
      failedMatches,
      ambiguousMatches,
      defined(timeColumn) ? timeColumn.timeIntervals : undefined,
      time
    );
    return regionIndices;
  }
docs: Returns an array the same length as regionProvider.regions, mapping each region into the relevant index into the table data source.
  Takes the current time into account if a time is provided, and there is a time column with timeIntervals defined.
  @private
  @param {RegionMapping} regionMapping The table data source.
  @param {JulianDate} [time] The current time, eg. terria.clock.currentTime. NOT the time column's ._clock's time, which is different (and comes from a DataSourceClock).
  @param {Array} [failedMatches] An optional empty array. If provided, indices of failed matches are appended to the array.
  @param {Array} [ambiguousMatches] An optional empty array. If provided, indices of matches which duplicate prior matches are appended to the array.
  @return {Array} An array the same length as regionProvider.regions, mapping each region into the relevant index into the table data source.