Add stubs for the math functions.

src/bin.rs

@@ -439,6 +439,34 @@ impl CompareContextElement for serde_json::Value {
             .map(IceResult::from_owned),
         }
     }
+
+    fn math_subtract<'a>(&self, other: &dyn ContextElement) -> Option<IceResult<'a>> {
+        todo!()
+    }
+
+    fn math_multiply<'a>(&self, other: &dyn ContextElement) -> Option<IceResult<'a>> {
+        todo!()
+    }
+
+    fn math_divide<'a>(&self, other: &dyn ContextElement) -> Option<IceResult<'a>> {
+        todo!()
+    }
+
+    fn math_modulus<'a>(&self, other: &dyn ContextElement) -> Option<IceResult<'a>> {
+        todo!()
+    }
+
+    fn math_abs<'a>(&self) -> Option<IceResult<'a>> {
+        todo!()
+    }
+
+    fn math_floor<'a>(&self) -> Option<IceResult<'a>> {
+        todo!()
+    }
+
+    fn math_ceil<'a>(&self) -> Option<IceResult<'a>> {
+        todo!()
+    }
 }
 
 #[derive(Debug)]