let marketNames = [| "# 0"; "# 1"; "# 2"; "# 3" |]

    let lookupMarketId =
        function
        | "# 1" -> Choice1Of2 1
        | "# 2" -> Choice1Of2 2
        | marketName -> Choice2Of2 (sprintf "Unable to lookup market '%s'" marketName)

    let marketIds = ?
    let marketErrors = ?