\begin{tabbing}
ecl{-}base{-}tuple($k$;${\it test}$)
\\[0ex]$\,\equiv$$_{\mbox{\scriptsize def}}$$\;\;$\=$\langle$$\mathbb{B}$\+
\\[0ex]$,\,$[$k$]
\\[0ex]$,\,$false$_{2}$
\\[0ex]$,\,$($\lambda$${\it k'}$,$s$,$v$,$x$. ${\it k'}$ = $k$ $\wedge_{2}$ ${\it test}$($s$,$v$) $\vee_{2}$ $x$)
\\[0ex]$,\,$($\lambda$$n$,$x$. $x$ $\wedge_{2}$ $n$=$_{2}$0)
\\[0ex]$,\,$($\lambda$$n$,${\it k'}$,$s$,$v$,$x$. false$_{2}$)
\\[0ex]$,\,$nil$\rangle$
\-
\end{tabbing}