(a) Unless otherwise agreed to in writing, a seller, buyer, lessor, or lessee is not considered to have knowledge or notice of a fact known by a real estate licensee of the seller, buyer, lessor, or lessee unless the fact is actually known by the seller, buyer, lessor, or lessee.
(b) Unless otherwise agreed to in writing, a real estate licensee does not have knowledge or notice of a fact that is not actually known by the licensee.