diff --git a/src/common.rs b/src/common.rs
index 78f9fbf64..7750d9ea5 100644
--- a/src/common.rs
+++ b/src/common.rs
@@ -34,3 +34,8 @@ macro_rules! xx {
 		From::from(From::from($x))
 	}
 }
+
+pub fn flush(s: String) {
+	::std::io::stdout().write(s.as_bytes()).unwrap();
+	::std::io::stdout().flush().unwrap();
+}