public V remove(int index) {
        return remove(get(index));
    }
Removes the element at the specified index.

@param index the index of the object to remove
@return the previous value corresponding the <code>key</code>,
        or <code>null</code> if none existed
@throws IndexOutOfBoundsException if the index is invalid
jphp-runtime/src/php/runtime/common/collections/map/LinkedMap.java