class_docstr: For storing and accessing flags.
code: def set_if_empty(self, key, val):
      if key not in self:
          self[key] = val
  
file_path: magenta/magenta/models/gansynth/lib/flags.py
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import base64
  import json
label_desc: Use image node_id 5 for calling the Flags obj's underlying member method code with example usage: obj.set_if_empty(key, val) without return types