== cobalt/io/sleep.hpp

The sleep operations are convenience wrappers for timers.
Every sleep operation creates a timer,
so it is generally more efficient to reuse a timer.

[source,cpp]
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// Waits using a steady_timer.
template<typename Duration>
inline auto sleep(const std::chrono::time_point<std::chrono::steady_clock, Duration> & tp);

// Waits using a system_timer.
template<typename Duration>
inline auto  sleep(const std::chrono::time_point<std::chrono::system_clock, Duration> & tp);

// Waits using a steady_timer.
template<typename Rep, typename Period>
inline auto sleep(const std::chrono::duration<Rep, Period> & dur);
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