The following code example is taken from the book
C++ Move Semantics - The Complete Guide by Nicolai M. Josuttis, Leanpub, 2020
The code is licensed under a Creative Commons Attribution 4.0 International License. Creative Commons License

// raw code

#include <iostream>
#include <string>
#include <vector>

template<typename T>
void insert(T& coll, typename T::value_type&& arg)

int main()
  std::vector<std::string> coll;
  insert(coll, std::string{"prvalue"});  // OK
  std::string str{"lvalue"};
  insert(coll, str);              // ERROR: T::value_type&& is not a universal reference
  insert(coll, std::move(str));   // OK