Bonds is a
direct subtype of Bond with functions Bonds Functions, keys Bonds keys and example object Bonds#1 that represents a collection of bonds.
This type has been made a
direct subtype of Bond primarily for technical reasons.
This inheritance permits all
local functions of the Bond type to be applicable to objects of the type here, too.
For example, the function
Yield also applies to a bond collection and returns the yields of all bonds in the collection.