public function buildForm(array $form, FormStateInterface $form_state) { 
       $form['#tree'] = true;
       $form['#prefix'] = '
';
       $form['#suffix'] = '';
       $form['#cache'] = ['max-age' => 0];
       $nb_sponsee = $form_state->get('nb_sponsee');
       $form['sponsees'] = [
    	 '#type' => 'container',
    	 '#prefix' => '
',
    	  '#suffix' => '',
       ];  
      $class ='member';
        for ($i = 0; $i < $nb_sponsee; $i++) {   	
           $form['sponsees'][$i]['sponsee'] = [
        	    '#type' => 'fieldset',
        	     '#title' => $this->t('Your Account'),
        	     ''#attributes' => [
              	'class' => $class,
         	     ],
    	];	
         $form['sponsees'][$i]['sponsee']['firstname'] = [
        	     '#prefix' => '
',
        	    '#suffix' => '',
        	    '#type' => 'textfield',
                '#title' => $this->t('First Name'),
        	    '#placeholder' => $this->t('Firstname'),
        	   '#maxlength' => 64,
        	   '#size' => 64,
        	   '#required'    	 => TRUE,
        ];
       $form['sponsees'][$i]['sponsee']['last name'] = [
        	'#type' => 'textfield',
        	'#title' => $this->t('Last Name'),
        	'#placeholder' => $this->t('Last Name'),
        	'#maxlength' => 64,
        	'#size' => 64,
        	'#required' => TRUE,        		 
      ];
     	$form['sponsees'][$i]['sponsee']['dob'] = [
        	'#type' => 'date',
        	'#title' => $this->t('Date Of Birth'),
        	'#placeholder' => $this->t('Date Of Birth'),   
        	'#required'=> TRUE,  
    	];
     	$form['sponsees'][$i]['sponsee']['email'] = [
        	    '#type' => 'email',
                '#title' => $this->t('Email Address'),
        	     '#placeholder' => $this->t('Email Address'),
                 '#required' => TRUE,        
    	];
    	$form['sponsees'][$i]['sponsee']['phone'] = [
        	        '#type' => 'textfield',
        	        '#title' => $this->t('Telephone Number'),
        	        '#placeholder' => $this->t('Telephone Number'),
        	        '#maxlength' => 64,
        	        '#size' => 64,
        	      '#disabled' => $disabled, 	 
    	];
    	$form['sponsees'][$i]['sponsee']['street_house'] = [
        	       '#type' => 'textfield',
        	       '#title' => $this->t('Street and House Number'),
        	       '#placeholder' => $this->t('Street and House Number'),
        	        '#maxlength' => 64,
        	        '#size' => 64,    
        	        '#required'    	 => TRUE,            	    	 
    	];
    	$form['sponsees'][$i]['sponsee']['postal_code'] = [
        	      '#type' => 'textfield',
        	       '#title' => $this->t('Postal Code'),
        	      '#placeholder' => $this->t('Postal Code'),
        	      '#maxlength' => 64,
        	     '#size' => 64,
        	       '#required' => TRUE,    
           	];
         $form['sponsees'][$i]['sponsee']['place'] = [
        	         '#type' => 'textfield',
        	       '#title' => $this->t('Place'),
        	      '#placeholder' => $this->t('Place'),
        	       '#maxlength' => 64,
        	       '#size' => 64,        	
        	      '#required' => TRUE,    
        ];