From cppreference.com
std::stop_token&operator=(conststd::stop_token&other)noexcept; (1) (since C++20)std::stop_token&operator=(std::stop_token&&other)noexcept; (2) (since C++20)Replaces the associated stop-state with that of other.
1) Copy-assigns the associated stop-state of other to that of *this. Equivalent to stop_token(other).swap(*this).
2) Move-assigns the associated stop-state of other to that of *this. After the assignment, *this contains the previous associated stop-state of other, and other has no associated stop-state. Equivalent to stop_token(std::move(other)).swap(*this).
Parameters
other - another stop_token object to share the stop-state with to or acquire the stop-state from