Forcing a type check

gistfile1.go

package main                                                                           
                                                                                       
import (                                                                               
    "fmt"                                                                              
)                                                                                      
                                                                                       
type Boo interface{ Write(int32) int32 }                                               
                                                                                       
type Babi struct {}                                                                    
                                                                                       
func boo(b Boo) {                   
  fmt.Println(b.Write(99))                                                             
}                                                                                      
                                                                                       
func main() {                                                                          
  var u int64 = -0x80000000                                                            
  fmt.Println(u)                                                                       
  fmt.Println(u << 1)                                                                  
  var _ Boo = Babi{} // performs type checking                                         
}