code: def generic_visit_pdvega_plot(self, node):
      # TODO: generate PNGs and insert them here
      if "alt" in node.attributes:
          self.body.append(_("[ graph: %s ]") % node["alt"])
      else:
          self.body.append(_("[ graph ]"))
      raise nodes.SkipNode
  
imports: import os
  import json
  import warnings
  import jinja2
  from docutils import nodes
  from docutils.parsers.rst import Directive
  from docutils.parsers.rst.directives import flag, unchanged
  from sphinx.locale import _
  from pdvega import Axes
  from .utils import exec_then_eval
label_desc: Use image node_id 4 for calling a global function with example usage: generic_visit_pdvega_plot(node) without return types