Should use %v for functions, not %s
Should use %v for functions, not %s

```go vet``` complaints about the current implementation:
```accumulate_test.go:27: arg test.converter for printf verb %s of wrong type: func(string) string```

%#v is a best fit for this

leenipper/xgo,pminten/xgo,robphoenix/exercism-go,exercism/xgo,robphoenix/exercism-go,leenipper/xgo,exercism/xgo,pminten/xgo