Debug help - delegate from dlang Tour

[Brother Bill]

https://tour.dlang.org/tour/en/basics/delegates

This is so simple.  What is D complaining about?
Should this also work with a Template, as shown?

```
import std.stdio;

void main()
{
	// auto add(T)(T lhs, T rhs)
	// {
	// 	return lhs + rhs;
	// }

	int add(int lhs, int rhs) {
		return lhs + rhs;
	}

	int doSomething(int function(int, int) doer)
	{
		// call passed function
		return doer(5, 6);
	}

	doSomething(&add);

}

```

Console output:
```
c:\dev\D\D_templates_tutorial\toy1\source\app.d(20): Error: 
function `doSomething` is not callable using argument types `(int 
delegate(int lhs, int rhs) pure nothrow @nogc @safe)`
     doSomething(&add);
                ^
c:\dev\D\D_templates_tutorial\toy1\source\app.d(20):        
cannot pass argument `&add` of type `int delegate(int lhs, int 
rhs) pure nothrow @nogc @safe` to parameter `int function(int, 
int) doer`
c:\dev\D\D_templates_tutorial\toy1\source\app.d(14):        
`app.main.doSomething(int function(int, int) doer)` declared here
     int doSomething(int function(int, int) doer)
         ^
```