std::shared_future<T>::operator=
Min standard notice:
Assigns the contents of another shared_future.
# Declarations
shared_future& operator=( const shared_future& other );
(since C++11) (until C++17)
shared_future& operator=( const shared_future& other ) noexcept;
(since C++17)
shared_future& operator=( shared_future&& other ) noexcept;
(since C++11)
# Parameters
other: a std::shared_future that will transfer state to *this
# Return value
*this