std::generator<Ref,V,Allocator>::begin
Min standard notice:
Pushes coroutine_ into *active_ stack, then evaluates coroutine_.resume().
# Declarations
/*iterator*/ begin();
(since C++23)
# Return value
An iterator whose coroutine_ member refers to the same coroutine as coroutine_ does.
# Notes
It is an undefined behavior to call begin() more than once on the same generator object.
# Example
This section is incompleteReason: no example