code: async def next(self) -> Any:
          
          # So, if we're at BOF, we need to skip till the boundary.
          if self._at_eof:
              return
          await self._maybe_release_last_part()
          if self._at_bof:
              await self._read_until_first_boundary()
              self._at_bof = False
          else:
              await self._read_boundary()
          if self._at_eof:  # we just read the last boundary, nothing to do there
              return
          self._last_part = await self.fetch_next_part()
          return self._last_part
docs: Emits the next multipart body part.