code: def _get_image_numpy_dtype(self):
          
          try:
              ftype = self._info['img_equiv_type']
              npy_type = _image_bitpix2npy[ftype]
          except KeyError:
              raise KeyError("unsupported fits data type: %d" % ftype)
  
          return npy_type
docs: Get the numpy dtype for the image