difference between x = Nullable.init and x.nullify

[vit via Digitalmars-d-learn]

Hello,
What's the difference between x = Nullable!Test.init and 
x.nullify?


class Test{}

void test()pure nothrow{
    Nullable!Test x;

    x = Nullable!Test.init; //OK
    x.nullify;              //Error: function 
'std.typecons.Nullable!(Test).Nullable.nullify!().nullify' is not 
nothrow

}