I have a spreadtab table and want to sum one of it's columns. I would like to use the result several times in my document. How do I go about doing that?

This code should explain what I am trying to accomplish.

```
\documentclass[a4paper]{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{spreadtab}
\usepackage{booktabs}

\begin{document}
\begin{spreadtab}{{tabular}{ll}}
  \toprule @Col1 & @Col2 \\
  \midrule 
  2 & 2 \\
  3 & 3 \\
  \bottomrule   
  \newcommand{\totsum}{:={sum(b2;b3)}}
  & \totsum \\
\end{spreadtab}

Here I am using totsum outside of the table: \totsum \\
\end{document}

```