docs: def _process_content_header(self, channel, payload):
          """
          Process Content Header frames
  
          """
          partial = self.partial_messages[channel]
          partial.add_header(payload)
  
          if partial.complete:
              #
              # a bodyless message, we're done
              #
              self.queue.put((channel, partial.method_sig, partial.args, partial.msg))
              del self.partial_messages[channel]
              self.expected_types[channel] = 1
          else:
              #
              # wait for the content-body
              #
              self.expected_types[channel] = 3