module Mail::MessageIds

def _nt_primary
  start_index = index
  if node_cache[:primary].has_key?(index)
    cached = node_cache[:primary][index]
    @index = cached.interval.end if cached
    return cached
  end
  r0 = _nt_message_ids
  r0.extend(Primary0)
  node_cache[:primary][start_index] = r0
  r0
end

def root
  @root ||= :primary
end