Use template functions inside template

I want to implement the following for more than one (i.e. many) functions (function1(), function2(), ...etc.).

Currently I have it separately as follows:

template <typename T>concept iterator_1 = requires(T const& t) {  t.function1();};

template <iterator_1 R>static float getterFunction(R const& r){  return r.function1();}

template <typename T>concept iterator_2 = requires(T const& t) {  t.function2();};

template <iterator_2 R>static float getterFunction(R const& r){  return r.function2();}

I want to use a general getterFunction to choose function1(), function2(), ...etc. with an if condition, such as follows:

template <typename A>float getterFunction(A const& a){  auto i = -1;  if (something==0) {    i = a.function1();  }   else if (something==1) {    i = a.function2();  }  else if {    ...  }  return i;}

I would like to use this general getterFunction as follows:

template <typename B> void DoSomething(typename B::iterator const& b){  float value = getterFunction(b);  ...}

I was wondering if there is a more general way of doing this, instead of writing many concepts for each of the many functions?