code: public static ImmutableVector2 copy(Vector2 source) {
  		if (source instanceof ImmutableVector2) return (ImmutableVector2)source;
  		return createVector(source.getX(), source.getY());
  	}
docs: Returns an immutable vector with the same values as the argument.
  
  @param source the vector containing the data for the new immutable vector
  @return an immutable vector containing the same elements as {@code source}
  @throws NullPointerException if {@code source} is {@code null}