theming – #theme_wrappers do not wrap the #theme template

I want to wrap the #theme model with the help of a #theme_wrapper model:

    // Call the saved theme
function _drupal7_test_fb_config_form () {
$ theme = [
        '#theme' => 'fb_users',
        '#theme_wrappers' => array('fb_users_wrapper'),
        '#item_1' => 'value of item 1',
        '#item_2' => 'value of item 2',
    ];
return $ theme;
}

the #theme is rendered correctly using & # 39;theme_fb_users& # 39 ;, and also the theme of the packaging but $ render_array[‘#children’] is empty? I assumed that it would contain the #theme html template:

//#theme
function theme_fb_users ($ variables) {
$ render_array = $ variables['render_array'];
echo "
    "; echo "
  • {$ render_array['#item_1']}
  • "; echo "
  • {$ render_array['#item_2']}
  • "; echo "
"; } // # theme_wrappers function theme_fb_users_wrapper ($ variables) { $ render_array = $ variables['render_array']; // this does not pack the #theme, bc $ render_array['#children'] is empty echo "
{$ render_array['#children']}
"; } // Definition of themes drupal7_test_theme function ($ existing, $ type, $ theme, $ path) { $ themes['fb_users'] =[ 'render element' => 'render_array' ]; $ themes['fb_users_wrapper'] =[ 'render element' => 'render_array' ]; returns $ themes }

I found the solution if someone interested:
the HTML output of #theme function , will be passed function #theme_wrapper through the $ render_array[‘#children’] so it works:

// # theme template: does not output the HTML code but returns it for later uploading into #theme_wrappers
function theme_fb_users ($ variables) {
$ render_array = $ variables['render_array'];
$ output = "

users

"; $ output. = "
    "; $ output. = "
  • {$ render_array['#item_1']}
  • "; $ output. = "
  • {$ render_array['#item_2']}
  • "; $ output. = "
"; return $ output; } // # theme_wrappers: the return of the function #theme will be passed to the function #theme_wrappers $ render_array['#children'] function theme_fb_users_wrapper ($ variables) { $ render_array = $ variables['render_array_wrapper']; // this does not pack the #theme, bc $ render_array['#children'] is empty echo "
{$ render_array['#children']}
"; } // Definition of themes drupal7_test_theme function ($ existing, $ type, $ theme, $ path) { $ themes['fb_users'] =[ 'render element' => 'render_array' ]; $ themes['fb_users_wrapper'] =[ 'render element' => 'render_array_wrapper' ]; returns $ themes }