# Update a hash by adding or replacing mappings. Hash references
# stored in the top level hash can be updated recursively, if desired.
# Params:
#   %h      = The hash to modify
#   $depth = Recursion depth.
#   @kv     = New key value pairs.
sub hpush(\%$@);
sub hpush(\%$@) {
    my ($h, $depth, @kv) = @_;
    
    while (@kv) {
	my ($k, $v) = splice @kv, 0, 2;
	
	if ($depth > 0 and ref($h->{$k}) eq 'HASH' and ref($v) eq 'HASH') {
	    hpush %{$h->{$k}}, $depth - 1, %{$v};
	}
	else {
	    $h->{$k} = $v;
	}
    }
}