sub t1{ return "t1:",\&t1; }
sub t2{ *t2=\&t1 if @_; return "t2:",\&t2; }

print t1(), t2();
t1: CODE(0x1bd2940) t2: SCALAR(0x1bd53c8)

print t1(), t2();
t1: CODE(0x1bd2940) t2: SCALAR(0x1bd53c8)

print t1(), t2(), t2('change it');
Subroutine t2 redefined at (eval 47) line 1, <> line 50.
t1: CODE(0x1bd2940) t2: SCALAR(0x1bd53c8) t2: SCALAR(0x1bd53c8)

print t1(), t2();
t1: CODE(0x1bd2940) t1: CODE(0x1bd2940)

##</code><code>##

sub t1{ return "t1:",\&t1; }
sub t2{ undef *t2 if @_; return "t2:",\&t2; }

print t1(), t2();
t1: CODE(0x1bd5200) t2: CODE(0x1bd5410)

print t1(), t2();
t1: CODE(0x1bd5200) t2: CODE(0x1bd5410)

print t1(), t2(), t2('change it');
t1: CODE(0x1bd5200) t2: CODE(0x1bd5410) t2: CODE(0x1bd52d8)