For multiline comments use pod² or void here-docs¹.

Beside leading underscore convention real private methods are introduced in newer Perl5 versions via my , all older allow putting a function ref into a private var.

 
my $private = sub { print "privat" };

$private->();
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All this has been extensively discussed in the past, did you try searching the archives?

updates

¹)

<<___;
bla
bla 
bla
___
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²)

print "huhu";

=for doc
bla
bla
bla
=cut

print "haha";
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