      \fitem{explode}(s:string): returns a tab containing the characters
      of the \code{s} (represented as string with only one element). For
      example:
      \begin{lstlisting}
            @explode("")  ->[]
            @explode("abc")  ->["a", "b", "c"]
            @reduce(@+, @explode("abc")) ->"abc"
            @scan(@+, @explode("abc")) ->["a", "ab", "abc"]
      \end{lstlisting}


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

