If only Nullables can be null, could we formally define this? isnull(x::Nullable) = x.isnull # already defined in nullable.jl isnull(x) = false # extra definition for everything else
> isnull( lp15 ) --> true > isnull( lp16 ) --> MethodError: `isnull` has no method matching isnull( > ::Date ) >
