go imap: bad sequence set value ""

I'm trying to follow the IMAP example but I get this error imap: bad sequence set value "" which corresponds with the line set, _ := imap.NewSeqSet("") from the example. Is it a bug in the lib or a typo in the documentation ?

I'm trying to fetch all the messages so setting the sequence to wildcard ( * ) doesn't seem to work either. I've also tried to read RFC with little success. All I could find about the sequence values is this

seq-number      = nz-number / "*"
                    ; message sequence number (COPY, FETCH, STORE
                    ; commands) or unique identifier (UID COPY,
                    ; UID FETCH, UID STORE commands).
                    ; * represents the largest number in use.  In
                    ; the case of message sequence numbers, it is
                    ; the number of messages in a non-empty mailbox.
                    ; In the case of unique identifiers, it is the
                    ; unique identifier of the last message in the
                    ; mailbox or, if the mailbox is empty, the
                    ; mailbox's current UIDNEXT value.
                    ; The server should respond with a tagged BAD
                    ; response to a command that uses a message
                    ; sequence number greater than the number of
                    ; messages in the selected mailbox.  This
                    ; includes "*" if the selected mailbox is empty.

seq-range       = seq-number ":" seq-number
                    ; two seq-number values and all values between
                    ; these two regardless of order.
                    ; Example: 2:4 and 4:2 are equivalent and indicate
                    ; values 2, 3, and 4.
                    ; Example: a unique identifier sequence range of
                    ; 3291:* includes the UID of the last message in
                    ; the mailbox, even if that value is less than 3291.

sequence-set    = (seq-number / seq-range) *("," sequence-set)
                    ; set of seq-number values, regardless of order.
                    ; Servers MAY coalesce overlaps and/or execute the
                    ; sequence in any order.
                    ; Example: a message sequence number set of
                    ; 2,4:7,9,12:* for a mailbox with 15 messages is
                    ; equivalent to 2,4,5,6,7,9,12,13,14,15
                    ; Example: a message sequence number set of *:4,5:7
                    ; for a mailbox with 10 messages is equivalent to
                    ; 10,9,8,7,6,5,4,5,6,7 and MAY be reordered and
                    ; overlap coalesced to be 4,5,6,7,8,9,10.

status          = "STATUS" SP mailbox SP
                  "(" status-att *(SP status-att) ")"

Here's the code you're copying from.

// Fetch the headers of the 10 most recent messages
set, _ := imap.NewSeqSet("")
if c.Mailbox.Messages >= 10 {
    set.AddRange(c.Mailbox.Messages-9, c.Mailbox.Messages)
} else {
    set.Add("1:*")
}
cmd, _ = c.Fetch(set, "RFC822.HEADER")

That code sets a variable to "" but never uses that value. It uses another value, which depends on the state of the c.Mailbox object.

The lesson here is that copying a single line from the documentation isn't enough, you need to look at the surroundings.

It seems there is a typo in the Go doc. set, err := imap.NewSeqSet("1:*") fixes the issue.