rf: ex and replace one statement with a couple of statements

hi,

I've tried to use rf ex to replace one statement with a pair of statements.

I tried the following:

      ex {
            import "gioui.org/op";
            import "gioui.org/op/clip";
    
            var o *op.Ops;
            var p clip.Path;
            var sty clip.StrokeStyle;
            var width float32;
    
            p.Stroke(width, sty).Add(o) ->  \
                    p.Op().Add(o)           \
                    clip.StrokeOp{          \
                            Width: width,   \
                            Cap: sty.Cap,   \
                            Join: sty.Join, \
                    }.Add(o);
      }

ie: replacing:

p.Stroke(width, sty).Add(o)

with:

p.Op().Add(o)
clip.StrokeOp{
    Width: width,
    Cap: sty.Cap,
    Join: sty.Join,
}

trying to run the above ex script, I get:

$> rf ex ...
ex: missing substitution in example: p.Stroke(width, sty).Add(o) ->

is this something that should be possible to achieve with rf ex (or with rf at all) ?

Start with the rf ex example parser and reproduce the reported "missing substitution" error using the statement replacement shown in the issue. Determine whether an ex example can represent one statement replaced by multiple statements; done means the requested replacement is accepted and produces the two statements shown.