anchor.diff:    </form>
   </div>])))
   
  +(defun password? (pw)
  +  (and pw (not (< (length pw) 8))))
  +
   (defun email-address? (str)
     (and str (not (string= str ""))))
   
  
positive.code:           ((not (email-address? email))             (err "email"))
            ((check-password password *account*)
             (update-account *account*
                             account-email email)     #/site/preferences-ok)
            (t                                        (err "pw")))))
  
  (defpage /site/preferences "Account preferences" (email error)
    (if *account*
        (progn
          #H[<h3>Change account preferences</h3>
          <form id="changemail" class="prefs" method="post"
                action="$(#/site/change-email)">
          <dl>]
            (maybe-show-form-error error "email" "Bad email address")
  
negative.code:           <dd><input class="regin" type="text" name="email" title="new email"
                       value="${(if email email "")}" /></dd>]
            (maybe-show-form-error error "pw" "Wrong password")
            #H[<dt><label for="password">Enter password:</label></dt>
            <dd><input class="regin" type="password" name="password" /></dd>
            <dt /><dd><input type="submit" value="change email" /></dd>
          </dl>
  