-->
sequence s = {{"grass","green"},{"snow","white"},{"sky","blue"},{"cherry","red"},{0,1.2},{3.4,-1}}
?sort(s)
function compare_col2(sequence a, b) return compare(a[2],b[2]) end function
?custom_sort(compare_col2,s)
?sort_columns(s,{2}) -- 0.8.0+, same result as above w/o needing an explicit comparison routine