class Net::IMAP::MessageSet

def initialize(data:)
  super
  warn("DEPRECATED: #{MessageSet} should be replaced with #{SequenceSet}.",
       uplevel: 1, category: :deprecated)
  begin
    # to ensure the input works with SequenceSet, too
    SequenceSet.new(data)
  rescue
    warn "MessageSet input is incompatible with SequenceSet: [%s] %s" % [
      $!.class, $!.message
    ]
  end
end