// http://grepcode.com/file/repository.grepcode.com/java/root/jdk/openjdk/8u40-b25/java/lang/Comparable.java#Comparable
// El Comparable.java original tiene:
// package java.lang;
// import java.util.*;
public interface Comparable<T> {
    /**
     * @param o the object to be compared.
     * @return a negative integer, zero, or a positive integer as this object
     *          is less than, equal to, or greater than the specified object.
     * @throws NullPointerException if the specified object is null
     * @throws ClassCastException if the specified object's type prevents it
     *          from being compared to this object.
     */
    public int compareTo(T o);
}
