let $a$,$b$,$c$,$d$,$e$ = $u$ in $v$($a$;$b$;$c$;$d$;$e$)
\\[0ex]$\,\equiv$$_{\mbox{\scriptsize def}}$$\;\;$let $a$,${\it zz}_{1}$ = $u$ in let $b$,${\it zz}_{2}$ = ${\it zz}_{1}$ in let $c$,${\it zz}_{3}$ = ${\it zz}_{2}$ in let $d$,$e$ = ${\it zz}_{3}$ in $v$($a$;$b$;$c$;$d$;$e$)