getShortestName method
Returns the shortest name for the units. This will be the first non-null name
found when inspecting secondary abbreviation, primary abbreviation and full name,
in that order. If sing
is true and no symbol or alternate name are available
then the singular version of the name will be returned.
Implementation
String getShortestName(bool sing) =>
abbrev2 ?? abbrev1 ?? (sing ? singular : name);