class_docstr: A custom Vega-Lite display object.
code: def _generate_js(self, id, **kwds):
      template = utils.get_content(self.JS_TEMPLATE)
      payload = template.format(
          id=id,
          spec=json.dumps(self.spec, **kwds),
          opt=json.dumps(self.opt, **kwds),
          type=self.render_type,
      )
      return payload
  
file_path: ipyvega/vega/base.py
imports: from __future__ import absolute_import
  import json
  import uuid
  from IPython.display import display
  from .None import utils
label_desc: Use image node_id 3 for calling the VegaBase obj's underlying member method code with example usage: obj._generate_js(id) and returns: payload