## btreeisbinary

### Instructions

Write a function, BTreeIsBinary, that returns true only if the tree given by root follows the binary search tree properties.

This function must have the following signature.

### Expected function

```go
func BTreeIsBinary(root *TreeNode) bool {

}
```

### Usage

Here is a possible [program](TODO-LINK) to test your function :

```go
package main

import (
	"fmt"
	student ".."
)

func main() {
	root := &student.TreeNode{Data: "4"}
	student.BTreeInsertData(root, "1")
	student.BTreeInsertData(root, "7")
	student.BTreeInsertData(root, "5")
	fmt.Println(student.BTreeIsBinary(root))
}
```

And its output :

```console
student@ubuntu:~/student/btreeisbinary$ go build
student@ubuntu:~/student/btreeisbinary$ ./btreeisbinary
true
student@ubuntu:~/student/btreeisbinary$
```