Derive `Eq/PartialEq` for `Spacing`
diff --git a/src/lib.rs b/src/lib.rs
index b7dd21a..0f7ee95 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -165,7 +165,7 @@
     }
 }
 
-#[derive(Copy, Clone, Debug)]
+#[derive(Copy, Clone, Debug, Eq, PartialEq)]
 pub enum Spacing {
     Alone,
     Joint,