If you're just adding 1 to each element then defining a separate sub is overkill:

% perl -de0

Loading DB routines from perl5db.pl version 1.32
Editor support available.

Enter h or `h h' for help, or `man perldebug' for more help.

main::(-e:1):    0
  DB<1> @a = (1, 2, 3)

  DB<2> x @a
0  1
1  2
2  3
  DB<3> x map { $_ + 1 } @a
0  2
1  3
2  4
  DB<4> q
%
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