Method sleep

exercise/logging/src/lib.rs:28–34

(&mut self)

        }
    }
    pub fn sleep(&mut self) {
        if self.sleeping {
            // 5. Use error!() to log a (non-fatal) error stating that the Frog is already asleep
        } else {
            self.sleeping = true;
        }
    }
}

impl Default for Frog {