anchor.diff:  
       // read again :{P
       let readUpdated = 
  -        ["id", box (id.ToString())] 
  +        ["id", box id] 
           |> query<Person> store "select data from Person where data->>'_id' = :id"
       updated |> should equal readUpdated.[0]
       Array.length readUpdated |> should equal 1
  
positive.code: 
      // read
      let read = 
          [ "id", box (id.ToString()) ] 
          |> query<Person> store "select data from Person where data->>'_id' = :id"
      o |> should equal read.[0]
      Array.length read |> should equal 1
  
negative.code:     // delete
      commit store [delete o._id o]
      let readDeleted = 
          ["id", box id] 
          |> query<Person> store "select data from Person where data->>'_id' = :id"
      Array.length readDeleted |> should equal 0
  
  