diff --git a/TODO b/TODO
index 8c9d4f25..e5ad1067 100644
--- a/TODO
+++ b/TODO
@@ -13,6 +13,14 @@
   plus VipsPool will be more natural with #2, I think, and things like
   vips_avg() have to be form #2
 
+  also, we have
+
+  	if( vips_call( "add", a, b, &c ) ||
+		vips_call( "add", a, c, &d ) )
+		return( -1 );
+
+  which is much closer to #2
+