(self, changes_chunk)
Should process given changes_chunk.

            Must return a tuple with first element as set of failed changes that
            should be reprocessed serially by pillow and second element as a list
            of (change, exception) tuples for failed changes that should not be
            reprocessed but for which exceptions are to be handled by handle_pillow_error
Should process given changes_chunk.
Should process given changes_chunk .
def process_changes_chunk(self, changes_chunk):
        """
        Should process given changes_chunk.

            Must return a tuple with first element as set of failed changes that
            should be reprocessed serially by pillow and second element as a list
            of (change, exception) tuples for failed changes that should not be
            reprocessed but for which exceptions are to be handled by handle_pillow_error
        """
        pass
def process_changes_chunk ( self , changes_chunk ) : pass