Several methods return tuples, not lists.

Doc/lib/libpoplib.tex

@@ -70,13 +70,13 @@ Get mailbox status.  The result is a tuple of 2 integers:
 
 \begin{methoddesc}{list}{\optional{which}}
 Request message list, result is in the form
-\code{['response', ['mesg_num octets', ...]]}.  If \var{which} is
+\code{(\var{response}, ['mesg_num octets', ...])}.  If \var{which} is
 set, it is the message to list.
 \end{methoddesc}
 
 \begin{methoddesc}{retr}{which}
 Retrieve whole message number \var{which}.  Result is in form 
-\code{['response', ['line', ...], octets]}.
+\code{(\var{response}, ['line', ...], \var{octets})}.
 \end{methoddesc}
 
 \begin{methoddesc}{dele}{which}
@@ -98,14 +98,15 @@ Signoff:  commit changes, unlock mailbox, drop connection.
 \begin{methoddesc}{top}{which, howmuch}
 Retrieves the message header plus \var{howmuch} lines of the message
 after the header of message number \var{which}. Result is in form 
-\code{['response', ['line', ...], octets]}.
+\code{(\var{response}, ['line', ...], \var{octets})}.
 \end{methoddesc}
 
 \begin{methoddesc}{uidl}{\optional{which}}
 Return message digest (unique id) list.
 If \var{which} is specified, result contains the unique id for that
 message in the form \code{'\var{response}\ \var{mesgnum}\ \var{uid}},
-otherwise result is list \code{['response', ['mesgnum uid', ...], octets]}.
+otherwise result is list \code{(\var{response}, ['mesgnum uid', ...],
+\var{octets})}.
 \end{methoddesc}