How can I access values of multiple select list in a form? I have a custom form in a custom module with multiple select:

$form['sponsors'] = array(
 '#type' =&gt; 'select',
 '#options' =&gt; $sponsors,
 '#multiple' =&gt; TRUE,
 '#size' =&gt; 20,
);


But I'm stumped how to access the submitted multiple values in the form_submit function. I tried to get the values by looping through the key (one guess was $form['values']['sponsors'][$key]) but no luck... anyone can point me in right direction would be appreciated!
in case whether the user may select more than one item, size value be written like this way:

'#size' =&gt; $multiple ? min(12, count($options)) : 0,


this is how used in (taxonomy.module).