public function addInterestGroup($name, $group_id = NULL)
    {

        $payload = array(
            'id' => $this->listId,
            'group_name' => $name,
            'grouping_id' => (NULL === $group_id) ? $this->grouping_id : $group_id,
        );

        $apiCall = 'lists/interest-group-add';
        $data = $this->requestMonkey($apiCall, $payload);
        $data = json_decode($data, true);
        if (isset($data['error']))
            throw new MailchimpAPIException($data);
        else
            return true;
    }
public function addInterestGroup($name, $group_id = NULL)
    {

        $payload = array(
            'id' => $this->listId,
            'group_name' => $name,
            'grouping_id' => (NULL === $group_id) ? $this->grouping_id : $group_id,
        );

        $apiCall = 'lists/interest-group-add';
        $data = $this->requestMonkey($apiCall, $payload);
        $data = json_decode($data, true);
        if (isset($data['error']))
            throw new MailchimpAPIException($data);
        else
            return true;
    }
public function addInterestGroup ( $ name , $ group_id = NULL ) { $ payload = array ( 'id' => $ this -> listId , 'group_name' => $ name , 'grouping_id' => ( NULL === $ group_id ) ? $ this -> grouping_id : $ group_id , ) ; $ apiCall = 'lists/interest-group-add' ; $ data = $ this -> requestMonkey ( $ apiCall , $ payload ) ; $ data = json_decode ( $ data , true ) ; if ( isset ( $ data [ 'error' ] ) ) throw new MailchimpAPIException ( $ data ) ; else return true ; }
Add a single Interest Group - if interest groups for the List are not yet enabled, adding the first group will automatically turn them on.

@link http://apidocs.mailchimp.com/api/2.0/lists/interest-group-add.php
@param string $name the interest group to add - group names must be unique within a grouping
@param int $group_id optional The grouping to add the new group to - get using listInterestGrouping() . If not supplied, the first grouping on the list is used.
@return boolean true on success
@throws MailchimpAPIException
Add a single Interest Group - if interest groups for the List are not yet enabled adding the first group will automatically turn them on .