>perl -le
"use warnings;
 ;;
 $empty_string = '';
 @ra = split ',', $empty_string;
 ;;
 $foo = $ra[3];
 $bar = $ra[5];
 print qq{'$foo' '$bar'};
"
Use of uninitialized value $foo in concatenation (.) or string at...
Use of uninitialized value $bar in concatenation (.) or string at...
'' ''