Help for this page
$ perl -MDevel::Peek -we '$a = undef; $b = undef; Dump($a); Dump($b)' SV = NULL(0x0) at 0x8191dc4 ... SV = NULL(0x0) at 0x8191ddc REFCNT = 1 FLAGS = ()
$ perl -MDevel::Peek -we '$a = 1; $b = 2; Dump ($a); Dump ($b)' SV = IV(0x8192edc) at 0x8191dbc ... REFCNT = 1 FLAGS = (IOK,pIOK) IV = 2