What does this log?

1const std = @import("std");
2fn double(x: anytype) @TypeOf(x) {
3    return x * 2;
4}
5pub fn main() void {
6    std.debug.print("{d}\n", .{double(@as(u8, 21))});
7    std.debug.print("{d}\n", .{double(@as(i32, -5))});
8}