$contacts{$contact} = &share( {} ); 
share( $contacts{$contact}{'a'} ); 
share( $contacts{$contact}{'inc_dnd'} ); 
share( $contacts{$contact}{'lock'} ); 
$contacts{$contact}{'a'} = 1; 
$contacts{$contact}{'inc_dnd'} = &share( {} ); 
$contacts{$contact}{'lock'} = 0;
[download]

In a thread, I try to execute
lock( $contacts{$user_id} );

##</code><code>##

share( $contacts{$contact}{'user_id'} ); 

##</code><code>##

is_shared ( $contacts{$user_id} )