Implement a virtual shopping-basket in the programming language of your choice (Java, Ruby, Elixir, JavaScript, ...). It should be possible to add items to the shopping-basket. Implementing a graphical user interface (GUI) is not necessary - it's enough to show the behavior using test cases.
The following `API` shows the desired interface/behavior in pseudo-code. The final implementation can deviate from that.
## API
A warehouse has a set of products with fixed prices