cpp/utility/tuple/tuple cat

Constructs a tuple that is a concatenation of all tuples in. The element types of the returned tuple is formed by concatenating the elements type packs of all  types in  in order.

If any type in is not constructible from the type of the corresponding element in the sequence of elements concatenated from,.

Return value
A std object composed of all elements of all argument tuples constructed from for each individual element.