$ perl -MDevel::Peek -e'Dump $_ for 1'
SV = IV(0x816a408) at 0x814f6f0
  REFCNT = 2
  FLAGS = (PADBUSY,PADTMP,IOK,READONLY,pIOK)
  IV = 1

$ perl -MDevel::Peek -e'Dump $_ for 1..1'
SV = IV(0x816a40c) at 0x814ed9c
  REFCNT = 1
  FLAGS = (IOK,pIOK)
  IV = 1

##</code><code>##

$ perl -le'for (1..2) { map { print($_++) } 1..2 }'
1
2
2
3

$ perl -le'for (1..2) { for (1..2) { print($_++) } }'
1
2
1
2