Invalid indirect of type func (int) string

I'm getting stucked with the following error: ``` ./main.go:76: invalid indirect of Fizzbuzz (type func(int) string) ``` I understand that the Fizzbuzz function does not satisfy the writeString. My intuition is telling me that this is probably because I should be using an interface to Fizzbuzz? Can someone please give me some direction on how to execute this? What can I do to make this code Go idiomatic? ``` // -------------------------------INPUT-------------------------------------- // Your program should read an input file (provided on the command line), // which contains multiple newline separated lines. // Each line will contain 3 numbers which are space delimited. // The first number is first number to divide by ('A' in this example), // the second number is the second number to divide by ('B' in this example) // and the third number is where you should count till ('N' in this example). // You may assume that the input file is formatted correctly and the // numbers are valid positive integers. E.g. // 3 5 10 // 2 7 15 // -------------------------------OUTPUT------------------------------------ // Print out the series 1 through N replacing numbers divisible by 'A' by F, // numbers divisible by 'B' by B and numbers divisible by both as 'FB'. // Since the input file contains multiple sets of values, your output will // print out one line per set. Ensure that there are no trailing empty spaces // on each line you print. E.g. // 1 2 F 4 B F 7 8 F B // 1 F 3 F 5 F B F 9 F 11 F 13 FB 15 // ---------------------------PROPOSED SOLUTION----------------------------- package main import ( "bufio" "fmt" "log" "os" ) func Fizzbuzz(N int) (output string) { var ( A = N%3 == 0 B = N%5 == 0 ) switch { case A && B: output = "FB" case A: output = "F" case B: output = "B" default: output = fmt.Sprintf("%v", N) } return } func openFile(name string) *os.File { file, err := os.Open(name) if err != nil { log.Fatalf("failed opening %s for writing: %s", name, err) } return file } func Readln(r *bufio.Reader) { line, prefix, err := r.ReadLine() if err != nil { log.Fatalf("failed reading a line: %v", err) } if prefix { log.Printf("Line is too big for buffer, only first %d bytes returned", len(line)) } } func WriteString(w *bufio.Writer) { if n, err := w.WriteString(*Fizzbuzz); err != nil { log.Fatalf("failed writing string: %s", err) } else { log.Printf("Wrote string in %d bytes", n) } } func main() { file := openFile(os.Args[1]) defer file.Close() fi := bufio.NewReader(file) Readln(fi) fo := bufio.NewWriter(file) defer fo.Flush() WriteString(fo) } ``` Go-Playground