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From: Patricia Ferreira <pferreira@example.com>
Newsgroups: pt.comp.programacao
Subject: o resto =?utf-8?Q?=C3=A9?= Python
Date: Fri, 08 Mar 2024 18:36:46 -0300
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Preciso de um procedimento que testa (sem sequência) se dois valors u, s
são nulos.  Se forem, retorne NIL.  Se não for, obtenha uns valores.
Eis como fazer:

(defun last-time-seen (username)
  (let ((u (get-account username)))
    (and u (let ((s (account-seen u)))
             (and s (universal-to-human s))))))

Moleza.  Mas eis como um Lisper realmente faz:

(defun last-time-seen (username)
  (when-let* ((u (get-account username))
              (s (account-seen u))
    (universal-to-human s)))

When-let*.  Isso é linguagem de /programação/.  O resto é Python.