This package provides the Nullable type from Julia 0.6, which was removed in
subsequent versions. It also defines the unsafe_get and isnull functions, and all
methods previously implemented in Julia Base: get, eltype, convert, promote,
show, map, broadcast, filter, isequal, isless and hash.
The definitions of the above types and functions are conditional on the version of Julia
being used so that you can do using Nullables unconditionally and be guaranteed that
Nullable will behave as it did in Julia 0.6 in later releases.