asDateTimeString
The date-time from a tstr with tag Tagged.DATE_TIME_STRING.
Throws
if the data item isn't a tag with tag Tagged.DATE_TIME_STRING containing a tstr with valid date-time format according to RFC 3339.
The date-time from a tstr with tag Tagged.DATE_TIME_STRING.
if the data item isn't a tag with tag Tagged.DATE_TIME_STRING containing a tstr with valid date-time format according to RFC 3339.