std::span<T,Extent>::rbegin, std::span<T,Extent>::crbegin
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|   constexpr reverse_iterator rbegin() const noexcept;  | 
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|   constexpr const_reverse_iterator crbegin() const noexcept;  | 
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Returns a reverse iterator to the first element of the reversed span. It corresponds to the last element of the non-reversed span. If the span is empty, the returned iterator is equal to rend().
Parameters
(none)
Return value
Reverse iterator to the first element.
Complexity
Constant.
See also
|    returns a reverse iterator to the end   (public member function)  |