class Datum implements Comparable {

    String key;
    Object datum;

    public Datum(String key, Object o) { this.key = key; this.datum = o; }

    public Datum() { this.key = null; this.datum = null; }

    public int compareTo(Object o) { return key.compareTo(((Datum)o).key); }
    
    public boolean equals (Object o) { return key.equals(((Datum)o).key); }

    public String toString() { return key + " {" + datum.toString() + "}"; }
}