Test code an infra that implement the following.
- A way to represent money values along with currency using an underlying type selectable by the user.
- A way to include money items inside record fields, and ability to read items where each one of them might differ in the currency of the money values they contain.
- A way to ensure that money values of different currencies are not mixed up during various operations
- A way to do operations on money values without knowing the actual currency it is in and even convert it to another currency
- A way to define exchange rates using external sources as well as to be hard coded.