\begin{tabbing}
decrypt(${\it tab}$;${\it kval}$)
\\[0ex]$\,\equiv$$_{\mbox{\scriptsize def}}$$\;\;$\=${\it kval}$/$k$,$x$.\+
\\[0ex]if \=isl(st{-}lookup(${\it tab}$;$x$))$\rightarrow$\+
\\[0ex]outl(st{-}lookup(${\it tab}$;$x$))/${\it key}$,${\it data}$.
\\[0ex]if st{-}key{-}match(${\it tab}$;${\it key}$;$k$)$\rightarrow$ inl(${\it data}$) else inr($\cdot$) fi
\-\\[0ex]else inr($\cdot$) fi
\-
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