Effect of Instrument Altering Interest in Property Which was

Previously Disposed of by Will. If a testator who has made a testamentary disposition of property subsequently executes an instrument which alters his interest in such property, such instrument operates as a revocation of such testamentary disposition if:

(a)such instrument expresses the testator's intent that it shall be a revocation; or

(b)such instrument contains provisions wholly inconsistent with the terms of such testamentary disposition, unless such inconsistent provisions depend on a condition or contingency by reason of which such inconsistent provisions do not take effect.