code: func addValueFuncs(out map[string]reflect.Value, in FuncMap) {
  	for name, fn := range in {
  		v := reflect.ValueOf(fn)
  		if v.Kind() != reflect.Func {
  			panic("value for " + name + " not a function")
  		}
  		if !goodFunc(v.Type()) {
  			panic(fmt.Errorf("can't install method/function %q with %d results", name, v.Type().NumOut()))
  		}
  		out[name] = v
  	}
  }
docs: // addValueFuncs adds to values the functions in funcs, converting them to reflect.Values.