Wait for a certain length of time before an async function does any more work
function usleep( int $usecs, ): Awaitable<void>
This is similar to calling the PHP builtin
usleep funciton, but is
in the context of async, meaning that other
Awaitables in the async
scheduler can run while the async function that called
usleep() waits until
the length of time before asking to resume again.
$usecs- The amount of time to wait, in microseconds.