Converting the attributes from drupal 6 to drupal 7

Drupal 6:

$form['start_date'] = array(
'#type' => 'textfield',
'#title' => t('Tution Start Date'),
'#default_value' => '',
'#size' => 11,
'#attributes' => array('class' => 'tut_datepicker')
);

drupal 7:

$form['start_date'] = array(
'#type' => 'textfield',
'#title' => t('Tution Start Date'),
'#default_value' => '',
'#size' => 11,
'#attributes' => array('class' => array('tut_datepicker'))
);