Equal compares two nullable values and returns true if they are equal.

From a value which is considered 'set'.

FromNull constructs a value from a nullable value.

FromOmit constructs a value from a omittable value.

FromPtr creates a value from a pointer, if the pointer is null it will be 'null', if it has a value the deferenced value is stored.

Map transforms the value inside if it is set, else it returns a value of the same state.

Val allows representing a value with a state of "unset", "null", or "set".