Preserve original tokens of Signature
diff --git a/syntax/mod.rs b/syntax/mod.rs
index 6274cf1..7d2ca19 100644
--- a/syntax/mod.rs
+++ b/syntax/mod.rs
@@ -12,7 +12,7 @@
 mod tokens;
 pub mod types;
 
-use proc_macro2::{Ident, Span};
+use proc_macro2::{Ident, Span, TokenStream};
 use syn::{LitStr, Token};
 
 pub use self::atom::Atom;
@@ -57,6 +57,7 @@
     pub args: Vec<Var>,
     pub ret: Option<Type>,
     pub throws: bool,
+    pub tokens: TokenStream,
 }
 
 #[derive(Eq, PartialEq, Hash)]