docs: def _get_md5sum(self, fpath):
          """Calculate the md5sum of the specific image file"""
          try:
              current_md5 = hashlib.md5()
              if isinstance(fpath, six.string_types) and os.path.exists(fpath):
                  with open(fpath, "rb") as fh:
                      for chunk in self._read_chunks(fh):
                          current_md5.update(chunk)
  
              elif (fpath.__class__.__name__ in ["StringIO", "StringO"] or
                    isinstance(fpath, IOBase)):
                  for chunk in self._read_chunks(fpath):
                      current_md5.update(chunk)
              else:
                  return ""
              return current_md5.hexdigest()
          except Exception:
              msg = ("Failed to calculate the image's md5sum")
              LOG.error(msg)
              raise exception.SDKImageOperationError(rs=3)