What does this Zig snippet output?

1const std = @import("std");
2const Shape = union(enum) {
3    circle: f64,
4    square: f64,
5};
6pub fn main() void {
7    const s = Shape{ .circle = 3.0 };
8    switch (s) {
9        .circle => |r| std.debug.print("r={d:.0}\n", .{r}),
10        .square => |side| std.debug.print("s={d:.0}\n", .{side}),
11    }
12}