}
sub _init {}
-#sub clone { die "clone must be implemented in a child class" }
+
sub clone {
my $self = shift;
return ref($self)->new({
sub engine { $_[0]{engine} }
sub offset { $_[0]{offset} }
sub type { $_[0]{type} }
+sub staleness { $_[0]{staleness} }
sub load { die "load must be implemented in a child class" }