code: def _subArrayShape(self):
          
          if self._h5Dataset.dtype.fields is None:
              return tuple() # regular field
          else:
              fieldName = self.nodeName
              fieldDtype = self._h5Dataset.dtype.fields[fieldName][0]
              return fieldDtype.shape
docs: Returns the shape of the sub-array
              An empty tuple is returned for regular fields, which have no sub array.