docs: def to_bytes(self):
          '''
          Returns serialized bytes object representing all headers/
          payloads in this packet'''
          rawlist = []
          i = len(self._headers)-1
          while i >= 0:
              self._headers[i].pre_serialize(b''.join(rawlist), self, i)
              rawlist.insert(0, self._headers[i].to_bytes())
              i -= 1
          self._raw = b''.join(rawlist)
          return self._raw