scope(exit)
{
    assert(exists(deleteme));
    remove(deleteme);
}

int[] a = [ 0, 1, 1, 2, 3, 5, 8 ];
write(deleteme, a); // deleteme is the name of a temporary file
int[] b = [ 13, 21 ];
append(deleteme, b);
const bytes = read(deleteme);
const fileInts = () @trusted { return cast(int[]) bytes; }();
assert(fileInts == a ~ b);