std::ranges::subrange<I,S,K>::begin
From cppreference.com
                    
                                        
                    
                    
                                                            
                    |   constexpr I begin() const requires std::copyable<I>;  | 
(1) | (since C++20) | 
|   constexpr I begin() requires (!std::copyable<I>);  | 
(2) | (since C++20) | 
Obtains the iterator to the beginning of the subrange.
Return value
1) 
begin_.2) std::move(
begin_ ).Example
| This section is incomplete Reason: no example  | 
See also
|   obtains the sentinel  (public member function)  | |
|    (C++11)(C++14)  | 
  returns an iterator to the beginning of a container or array  (function template)  | 
|   (C++20)  | 
 returns an iterator to the beginning of a range (customization point object)  |