Some points worth noting about function naming

- Function name cannot start with a number
- Function names are case sensitive. Therefore, plus, Plus, and PLUS are different functions.
- Use camel case naming for function names, do not use underscores, and do not include spaces.
- The first letter is capitalized to distinguish between public functions and private functions. Public functions can be called outside the package, but private functions are not.

The following is a complete code example.

```
package main
import (
"fmt"
)
func plus(a int, b int) {
fmt.Println("a + b = ", a + b)
}
func Plus(a int, b int) {
fmt.Println("a + b = ", a + b)
}
func PlusPlus(a int, b int) {
fmt.Println("a + b = ", a + b)
}
func Plus123(a int, b int) {
fmt.Println("a + b = ", a + b)
}
func main() {
plus(1,1)
Plus(1,1)
PlusPlus(1,1)
Plus123(1,1)
}
```

Below is the program output:

```
a + b = 2
a + b = 2
a + b = 2
a + b = 2
```