go菜鸟：请各位大佬指点，代码哪里错了

``` package main import ( "fmt" "errors" "os" ) const rows, columns = 9, 9 type Grid [rows][columns]int8 func main() { var g Grid err := g.Set(6,2,5) if err != nil { fmt.Println("A",err) fmt.Printf("An error occurred: %v.\n", err) os.Exit(1) } } func (g *Grid) Set(row, column int, digit int8) error { if !inBounds(row, column) { return errors.New("out of bounds") } g[row][columns] = digit return nil } func inBounds(row, column int) bool { if row < 0 || row >= rows { return false } if column < 0 || column >= columns{ return false } return true } ``` 错误： #command-line-arguments ./a.go:26:10: invalid argument: array index 9 out of bounds [0:9]