Form constructor for the form_state_values_clean() test.
function form_test_form_state_values_clean_advanced_form($form, &$form_state) {
// Build an example form containing a managed file and a submit form element.
$form['image'] = array(
'#type' => 'managed_file',
'#title' => t('Image'),
'#upload_location' => 'public://',
'#default_value' => 0,
);
$form['submit'] = array(
'#type' => 'submit',
'#value' => t('Submit'),
);
return $form;
}