my $some_users = $collection->find->fields( { crt_by => 1, name  => 1, contacts => { '$slice' => 1 } } );
#my $some_users = $collection->find->limit( 1 )->fields( { crt_by => 1, name  => 1, contacts => 1 } );
#my $some_users = $collection->find_one( {}, { crt_by => 1, name  => 1, contacts => 1 } );