code: def _get_memmap(self):
          
  
          with open(self.filename) as fp:
  
              data_dtype = self._get_data_dtype()
              hdr_size = native_header.itemsize
  
              return np.memmap(fp, dtype=data_dtype,
                               shape=(self.mda['number_of_lines'],),
                               offset=hdr_size, mode="r")
docs: Get the memory map for the SEVIRI data