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//Conditionally toggle metabox' visibility if other metabox' checkbox is checked
function show_metaboxes_on_condition($checkbox, $toggled_box, inverse) {
	inverse = typeof inverse !== 'undefined' ? inverse : false;
	if ($checkbox.length && $toggled_box.length) {
		$toggled_box = $toggled_box.parents('.rwmb-field');
		$toggled_box.hide();
		if (inverse === false) {
			if ($checkbox.is(':checked')) {
				$toggled_box.show();
			}
		} else {
			if (!$checkbox.is(':checked')) {
				$toggled_box.show();
			}
		}
		$checkbox.on('change', function() {
			$toggled_box.toggle();
		});
	}
}

show_metaboxes_on_condition($('#lmmb_languages_is_closed'), $('#lmmb_languages_start_month'));