If the state associated with
*this contains a deferred function, invoke
the deferred function. Otherwise, wait until the asynchronous result
associated with an instance of
std::experimental::shared_future is ready.
void wait() const;
from multiple threads on
that share the same associated state are serialized. If the associated
state contains a deferred function then the first call to
invokes the deferred function and stores the returned value or
thrown exception as the asynchronous result.
Block until the asynchronous result associated with