std::reverse_iterator::operator[]
From cppreference.com
                    
                                        
                    < cpp | iterator | reverse iterator
                    
                                                            
                    |   /*unspecified*/ operator[](difference_type n) const;  | 
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Returns a reference to the element at specified relative location.
Contents | 
[edit] Parameters
| n | - | position relative to current location. | 
[edit] Return value
current[-n-1].
[edit] Examples
| This section is incomplete | 
[edit] See also
|    accesses the current element accesses a member of the current element (public member function)  | |