A.18.1 The Package Containers
The package Containers is the root of the containers
The library package
Containers has the following declaration:
Hash_Type is mod implementation-defined
type Count_Type is range 0 .. implementation-defined;
Hash_Type represents the range of the result of a
hash function. Count_Type represents the (potential or actual) number
of elements of a container.
Hash_Type'Modulus should be at least 2**32. Count_Type'Last
should be at least 2**31–1.