'Invalidates the cache that stores optimizations for traversing the
transform graph.  This is called automatically when transforms
are added or removed, but will need to be called manually if
weights on transforms are modified inplace.'

def invalidate_cache(self):

    self._cached_names_dct = None
    self._cached_frame_set = None
    self._cached_frame_attributes = None
    self._shortestpaths = {}
    self._composite_cache = {}
