* convertToFixedRange Transforms a `range of time` into a `fixed range of time`.
*
* The following types of a `ranges of time` can be represented:
*
* Fixed Range: A range with fixed start and end (e.g. "midnight January 1st 2020 to midday January 31st 2020")
* Anchored Range: A duration of time relative to a fixed point in time (e.g., "the 30 minutes before midnight January 1st 2020", or "the 2 days after midday on the 11th of May 2019")
* Rolling Range: A time range relative to now (e.g., "last 2 minutes", or "next 2 days")
* Open Range: A time range relative to an anchor (e.g., "before midnight on the 1st of January 2020", or "after midday on the 11th of May 2019")
*
* @param {Object} dateTimeRange - A Time Range representation
* It contains the data needed to create a fixed time range plus
* a label (recommended) to indicate the range that is covered.
*
* A definition via a TypeScript notation is presented below:
*
*
* type Duration = { // A duration of time, always in seconds
* seconds: number;
* }
*
* type Direction = 'before' | 'after'; // Direction of time relative to an anchor