c++ type deduction decltype template generic types

what does decltype do in c++? give me various ways to use it

In C++, decltype is a keyword introduced in C++11 that inspects the declared type of an expression. The result is the type itself, which can be used in various contexts, such as for declaring variables, function return types, template argument deduction, and more.

for now alive at

sk-experiments/cpp/experiments/curiously_recurring_template_pattern/main.cpp at…

give me the code, here you go