The valuation of these securities combines bond- or equity-valuation, as appropriate, with option pricing. For bonds here, there are two main approaches: (1) Depending on the type of option, the option price, as calculated using Black Scholes, is either added to or subtracted from the price of the "straight" bond (i.e. as if it had no optionality) and this total is then the value of the bond. (2) A bespoke "tree" (usually a lattice basedshort rate model) may be constructed where the option's effect is incorporated at each node in the tree, affecting either the bond price or the option price as specified; see further under bond option. Once the price has been calculated, the various yields can then be calculated for the security. Other securities with embedded derivatives are priced similarly.