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function cc_wpse_278096_disable_admin_bar() {
   if (current_user_can('administrator') || current_user_can('contributor') ) {
     // user can view admin bar
     show_admin_bar(true); // this line isn't essentially needed by default...
   } else {
     // hide admin bar
     show_admin_bar(false);
   }
}
add_action('after_setup_theme', 'cc_wpse_278096_disable_admin_bar');