code: async def blobize(self, elem=None, elem_type=None, params=None):
          
          if self.writing:
              await self.field(elem=elem, elem_type=elem_type, params=params)
              return bytes(self.iobj.buffer)
          else:
              return await self.field(elem=elem, elem_type=elem_type, params=params)
docs: Main blobbing
          :param elem:
          :param elem_type:
          :param params:
          :return: