View source for cpp/container/array/tuple element

===Example===
{{example
|code=
#include <array>
#include <tuple>
#include <type_traits>

int main()
{
    // define array and get the type of the element at position 0
    std::array<int, 10> data{0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
    using T = std::tuple_element<0, decltype(data)>::type; // int
    static_assert(std::is_same_v<T, int>);

    const auto const_data = data;
    using CT = std::tuple_element<0, decltype(const_data)>::type; // const int

    // the result of tuple_element depends on the cv-qualification of the tuple-like type
    static_assert(!std::is_same_v<T, CT>);
    static_assert(std::is_same_v<CT, const int>);
}
}}