Age at Release
prop("Released") .dateBetween( prop("Author") .first() .prop("Date of Birth"), "years" )
Age
now() .dateBetween( prop("Date of Birth"), "years" )
Age at Earliest
prop("Books") .map( current .prop("Released") .timestamp() ) .sort() .first() .fromTimestamp() .dateBetween( prop("Date of Birth"), "years" )
