text: /*
  Given a table customer holding customers information and the referee.
  
  +------+------+-----------+
  | id   | name | referee_id|
  +------+------+-----------+
  |    1 | Will |      NULL |
  |    2 | Jane |      NULL |
  |    3 | Alex |         2 |
  |    4 | Bill |      NULL |
  |    5 | Zack |         1 |
  |    6 | Mark |         2 |
  +------+------+-----------+
  Write a query to return the list of customers NOT referred by the person with id '2'.
  
  For the sample data above, the result is:
  
  +------+
  | name |
  +------+
  | Will |
  | Jane |
  | Bill |
  | Zack |
  +------+
  */
  # Write your MySQL query statement below
  SELECT name 
  FROM customer 
  WHERE referee_id IS NULL OR referee_id != 2;
  