anchor.diff:                  yield ldfld entDict
                   yield ldloc id
                   yield call0 (staticTemplate.GetMethod("Template"))
  -                yield call1 (entTemplate.GetMethod("CreateReader"))
  +                yield callvirt1 (entTemplate.GetMethod("CreateReader"))
                   yield dup
                   yield stloc entReader
                   yield call3'void (dictTy.GetMethod("Add", [| idTy; elemReaderTy |]))
  
positive.code:                 let! entReader = deflocal elemReaderTy
                  yield dup
                  yield ldfld entDict
                  yield ldloc id
                  yield ldloca entReader
                  yield call3 (dictTy.GetMethod("TryGetValue"))
  
negative.code:         zero // don't initialize dictionary yet
      override __.DefineProcessColumns() =
          cil {
              let! skip = deflabel
              yield ldarg 1 // column map
              match column with
              | Some column ->
  