def METHOD_NAME(mark):
    class BlockMarkerContextManager (object):
        def __init__ (self, mark):
            self._mark = mark
        def __enter__ (self):
            print('BEGIN:', mark)
            return None
        def __exit__ (self, exc_type, exc_value, traceback):
            print('END:', mark)
            return False
    return BlockMarkerContextManager (mark)