docs: def numpy(self):
          """ Grabs image data and converts it to a numpy array """
          # load GDCM's image reading functionality
          image_reader = gdcm.ImageReader()
          image_reader.SetFileName(self.fname)
          if not image_reader.Read():
              raise IOError("Could not read DICOM image")
          pixel_array = self._gdcm_to_numpy(image_reader.GetImage())
          return pixel_array