lab/lab9/lab9/MyHashMap.java
@Override
    public int size() {
        return size;
        // throw new UnsupportedOperationException();
    }
/* Returns the number of key-value mappings in this map. */
Returns the number of key-value mappings in this map.
Returns the number of key - value mappings in this map .
@Override
    public int size() {
        return size;
    }
@ Override public int size ( ) { return size ; }
Returns the number of key-value mappings in this map.
Returns the number of key - value mappings in this map .
// throw new UnsupportedOperationException();