SYNOPSIS

# e.g. tags => ["foo", "bar","bar"]
sort_field(tags) # tags => ["bar","bar","foo"]
sort_field(tags, uniq: 1) # tags => ["bar","foo"]
sort_field(tags, uniq: 1, reverse: 1) # tags => ["foo","bar"]
# e.g. nums => [ 100, 1 , 10]
sort_field(nums, numeric: 1) # nums => [ 1, 10, 100]
#push undefined values to the end of the list (default)
#beware: reverse has no effect on this!
sort_field(tags,undef_position: last)
#push undefined values to the beginning of the list
#beware: reverse has no effect on this!
sort_field(tags,undef_position: first)
#remove undefined values from the list
sort_field(tags,undef_position: delete)