Add showimp to commands.

lib/lib.go

@@ -45,3 +45,12 @@ func Err(exit int, err error, format string, a ...interface{}) {
 	fmt.Fprintf(os.Stderr, format, a...)
 	os.Exit(exit)
 }
+
+// CheckFatal calls Err if err isn't nil.
+func CheckFatal(err error, format string, a ...interface{}) {
+	if err == nil {
+		return
+	}
+
+	Err(ExitFailure, err, format, a...)
+}