What do you suppose this does?  when ( /INCREMENT/ ) { \&increment( @_ ) }

How about  \&increment( @_ )

$ perl -e " sub f { sub { @_ } } print \&f( 6,6,6 ); "
REF(0x3f9abc)
$ perl -e " sub f { sub { @_ } } print &f( 6,6,6 ); "
CODE(0x3f9b9c)
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So, if you're trying to return a reference, don't take a reference to that reference, simply return the reference

return increment( @_ );
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