diff --git a/src/protocol/ast.rs b/src/protocol/ast.rs
index 1c85a558741dd335dee6f3e89d60059b29e3ae9f..fb2a3c6cd3524b61af5ba30a3e9b10d9b3aa6950 100644
--- a/src/protocol/ast.rs
+++ b/src/protocol/ast.rs
@@ -1409,6 +1409,13 @@ impl ExpressionParent {
             _ => false,
         }
     }
+
+    pub fn as_expression(&self) -> ExpressionId {
+        match self {
+            ExpressionParent::Expression(id, _) => *id,
+            _ => panic!("called as_expression() on {:?}", self),
+        }
+    }
 }
 
 #[derive(Debug, Clone)]