code: def _create_dataset(
              self, group, chunk_size, compression, compression_opts):
          
          if chunk_size == 'auto':
              chunks = True
          else:
              # if dtype is a variable str, guess representative size is 20 bytes
              per_chunk = (
                  nb_per_chunk(20, 1, chunk_size) if self.dtype == np.dtype('O')
                  else nb_per_chunk(
                          np.dtype(self.dtype).itemsize, 1, chunk_size))
              chunks = (per_chunk,)
  
          shape = (0,)
          maxshape = (None,)
  
          # raise if per_chunk >= 4 Gb, this is requested by h5py
          group.create_dataset(
              self.name, shape, dtype=self.dtype,
              chunks=chunks, maxshape=maxshape, compression=compression,
              compression_opts=compression_opts)
docs: Create an empty dataset in a group.