Simple form.
function batch_test_simple_form() {
$form['batch'] = array(
'#type' => 'select',
'#title' => 'Choose batch',
'#options' => array(
'batch_0' => 'batch 0',
'batch_1' => 'batch 1',
'batch_2' => 'batch 2',
'batch_3' => 'batch 3',
'batch_4' => 'batch 4',
),
);
$form['submit'] = array(
'#type' => 'submit',
'#value' => 'Submit',
);
return $form;
}