Arguments in std::thread. How works?

Examples of use std::thread constructor:

#include <thread>
using namespace std;

void a_function(){}
void a_function2(int a){}
void a_function3(int a,int b){}
void a_function4(int &a){}

class a_class
{
public:
    void a_function5(int a){}
};

int main()
{
    a_class aux;
    int a = 2;

    thread t(a_function);
    thread t2(a_function2,2);
    thread t3(a_function3,2,3);
    thread t4(a_function4,ref(a));
    thread t5(&a_class::a_function5,&aux,2);

    t.join();
    t2.join();
    t3.join();
    t4.join();
    t5.join();
}

How can constructor knows number of arguments? How can constructor calls one unknown type of function? How could i implement something like that? By example, one wrapper for std::thread

class wrapper_thread
{
   thread t;

   public:

         wrapper_thread() //what arguments here?
         : t() //What arguments here?
         {}
}