diff --git a/src/lib.rs b/src/lib.rs
index 9c0641090..a111b5049 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -6,6 +6,8 @@ pub mod data;
 pub mod rank;
 pub mod tokenizer;
 mod common_words;
+mod shared_data_cursor;
+mod write_to_bytes;
 
 use serde_derive::{Serialize, Deserialize};
 
diff --git a/src/write_to_bytes.rs b/src/write_to_bytes.rs
new file mode 100644
index 000000000..4837eb6a3
--- /dev/null
+++ b/src/write_to_bytes.rs
@@ -0,0 +1,9 @@
+pub trait WriteToBytes {
+    fn write_to_bytes(&self, bytes: &mut Vec<u8>);
+
+    fn into_bytes(&self) -> Vec<u8> {
+        let mut bytes = Vec::new();
+        self.write_to_bytes(&mut bytes);
+        bytes
+    }
+}