Each function is characterized by the in which it belongs.
The key here specifies that Deriscope Type.
It is needed to distinguish between different that happen to share the same name.
For example, there exist several functions called , each belonging to a different Deriscope Type.
Therefore the function "Create" of Deriscope Type is different from the function "Create" of Deriscope Type
For , i.e. for functions associated with a particular , the key here is not needed, since the corresponding information can be deduced by the supplied object.