&duration, Function &f, bool period)
: timer_(io, duration),
duration_(duration),...&duration, Function &&f, bool period)
: timer_(io, duration),
duration_(duration),...&duration, Function &f,
std::size_t count)
: timer_(io, duration),...&duration, Function &&f,
std::size_t count)
: timer_(io, duration),...duration_(duration),
periodic_(true),
callback_(std::move(f)),
count_(count),