static auto _ = []()? [duplicate]

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• What is a lambda expression in C++11? 8 answers

static auto _ = [] (){        
    ios::sync_with_stdio(false);    
    cin.tie(NULL);    
    return nullptr;    
}();  

I know about the body sync and cin.tie but how does this static auto _ = []() work? what part of c++ this type of syntax belong?