code: def _add_constant(name, container=None):
      """add a constant to be defined
  
      optionally add it to one of the sets for use in get/setopt checkers
      """
      c = getattr(constants, name, _UNDEFINED)
      if c == _UNDEFINED:
          return
      globals()[name] = c
      __all__.append(name)
      if container is not None:
          container.add(c)
      return c
  
label_desc: Use image node_id 1 for calling a global function with example usage: _add_constant(name, container) and returns: c