Returns an empty option. @param <A> the type of the value @return an empty Option

Indicates whether some other object is "equal to" this Optional. The other object is considered equal if: <ul> <li>it is also an {@code Optional} and;

Returns the hash code value of the present value, if any, or 0 (zero) if no value is present. @return hash code value of the present value or 0 if no

Returns an Option containing the value. @param <A> the type of the value @param element contained value @return a new Option that contains the value

@return the value, if present, otherwise return {@code other} @param other the value to be returned if there is no value present