len => sub { my ($ref, $data, $len) = @_; ... ; return $newlen; },
clear => sub { my ($ref, $data) = @_; ... },
free => sub { my ($ref, $data) = @_, ... },
len => sub { my ($ref, $data, $len) = @_; ... ; return $newlen; },
clear => sub { my ($ref, $data) = @_; ... },
free => sub { my ($ref, $data) = @_, ... },