Drupal Mod Dev. Form API

form_fun.module file - this line does not appear in the code, obviously.

<?php

/*
 * Implements form hook_menu().
 */

function form_fun_menu() {
    $items = array();

    $items['form_fun/cake'] = array(
        'title' => 'Cake or Pie?',
        'page callback' => 'form_fun_cake_page',
        'access arguments' => array('access content'),
        'file' => 'form_fun.cake.inc',
        'weight' => 1,
    );
    return $items;
}

form_fun.cake.inc file - also just a note for reference.
<?php

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */

function form_fun_cake_page() {
    return drupal_get_form('form_fun_cake');
}

function form_fun_cake(&$form_state) {
    $form = array();

    $form['choice'] = array(
        '#type' => 'select',
        '#title' => t('Cake or pie?'),
        '#description' => t('Would you like cake or pie?'),
        '#options' => array(
            'cake' =>  t('Cake please'),
            'pie' => t('Pie I guess'),
        ),
        '#default' => 'cake',
        '#required' => TRUE,
    );

    $form['buttons']['submit'] = array(
        '#type' => 'submit',
        '#value' => t('Submit'),
    );

    $form['buttons']['unsure'] = array(
        '#type' => 'submit',
        '#value' => t('Equivocate'),
        '#submit' => array('form_fun_cake_unsure'),
        '#validate' => array(),

    );

    return $form;
}

function form_fun_cake_validate(&$form, &$form_state) {
  if($form_state['values']['choice'] == 'cake') {
      form_set_error('choice', t('We are out of cake.'));
  }
}

function form_fun_cake_submit(&$form, &$form) {
    dsm($form_state['values']);
    $form_state['redirect'] = '';
}

function form_fun_cake_unsure(&$form, &$form_state) {
    drupal_set_message(t('Make up your mind.'), 'warning' );
}

form_fun.info - file

name = Form FunApi Demonstration
description = Demonstrate the use of Form API.
core = 7.x
files[] = form_fun.cake.inc