Implement center block.

src/wasm/center_block.rs

@@ -7,6 +7,7 @@ use super::to_wasm::ToWasm;
 use super::AdditionalProperties;
 use crate::compare::ElispFact;
 use crate::types::CenterBlock;
+use crate::types::GetAffiliatedKeywords;
 use crate::wasm::to_wasm::ToWasmStandardProperties;
 
 #[derive(Debug, Serialize, Deserialize)]
@@ -21,8 +22,12 @@ to_wasm!(
     original,
     wasm_context,
     { WasmAstNode::CenterBlock(original) },
-    { "TODO".into() },
+    { "center-block".into() },
     {
+        let additional_properties = original
+            .get_affiliated_keywords()
+            .to_wasm(wasm_context.clone())?;
+
         let children = original
             .children
             .iter()
@@ -36,7 +41,7 @@ to_wasm!(
         Ok((
             children,
             WasmCenterBlock {
-                additional_properties: AdditionalProperties::default(),
+                additional_properties,
             },
         ))
     }