      \fitem{between}(a:numeric, x:numeric, b:numeric), \vListable. %%
      This function admits two special syntax and can be written
      \code{(x in a .. b)} (the parenthesis are mandatory).
      \label{fct:between}

      This predicate is true if \code{a < x < b}. If one argument is
      a tab, each scalar argument $u$ is extended into a tab whose all
      elements are equal to $u$ and the predicate returns true if it hold
      point-wise for all element of the tabs. For example:
      \begin{lstlisting}
            ([1, 2] in 0 .. 3)
      \end{lstlisting}
      returns true because \code{0 < 1 < 3} and \code{1 < 2 < 3}. 



      %%% -------------------------------------------------------

