num2shortmonth() #@ Convert number to abbreviated month name
{ #@ USAGE: num2month MONTHNUMBER [VAR]
local _num=${1#0} _var=$2
local _months=( '' Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec )
local _name=${_months[_num]}
is_var "$_var" &&
printf -v "$_var" %s "$_name" ||
printf '%s\n' "$_name"
}