$a contains ...
a 10<--
b a2 s2<--
c 30
c is -->a2 s2<--


$a contains ...
a 10<--
b<--
c 30
c is --><--


$a contains ...
a 10<--
b  <--
c 30
c is --><--


$a contains ...
a 10<--
b a2 s2  <--
c 30
c is -->a2 s2  <--