class Net::IMAP::ESearchResult

def all; data.assoc("ALL")&.last end

See also: #to_a

+IMAP4rev2+ {[RFC9051]}[https://www.rfc-editor.org/rfc/rfc9051.html#section-7.3.4].
Requires +ESEARCH+ {[RFC4731]}[https://www.rfc-editor.org/rfc/rfc4731.html#section-3.1] or

the +ALL+ return option was not specified but other return options were.
Returns +nil+ when the associated search command has no results, or when

satisfy the SEARCH criteria.
A SequenceSet containing all message sequence numbers or UIDs that

:call-seq: all -> sequence set or nil 
def all;        data.assoc("ALL")&.last        end