/*
 
                +---------------------------+
                | IPhList                   |
                +---------------------------+
                |IPhList remove(String name)|
                |IPhList add(PhEntry name)
                +---------------------------+
                             |
                            / \
                            ---
                             |
                -----------------------------
                |                           |
        +----------------+          +----------------+
        | MtPhList       |          | ConsPhList     |
        +----------------+          +----------------+
                                 +--| PhEntry first  |
                                 |  | IPhList  rest  |
                                 |  +----------------+
                                 |
                                 V
                        +----------------+
                        | PhEntry        |
                        +----------------+
                        | String  name   |
                        | int     num    |
                        +----------------+
                        
                        
*/

//to represent a list of phone entries
public interface IPhList {

  // remove the first phone entry with the given name from this list
  IPhList remove(String name);
}