Start explaining single type version
Problem with needed extra type only for vectors/maps
Advantage of initialization not requiring qualification for the chosen primary
initialization (but this might go away with future GNAT versions)

Overload Insert/Append and rely on distinct types => doesn't work as only the
last definition is recognized.

Need for separate types but recognized as one -> classwide family
Need for qualification (might be a bug in GNAT)
For indexing can be worked around with regular array for multi-maps
For mapping can be worked around with extra operator "/"

Mixed indexing?
   Literals and "/" to create the vector
