my ( $first, @list ) = @{my_list};
treat_1( $first );
treat_others( $_ ) for @list;

##</code><code>##

treat_1( shift @$my_list );
treat_others( $_ ) for @$my_list;

##</code><code>##

treat_1( $my_list->[0] );
treat_others( $my_list->[$_] ) for ( 1 .. $#{$my_list} );