code: def render(self):
      reader = {"name": "BlockMatrixPersistReader", "id": self.id}
      return escape_str(json.dumps(reader))
  
imports: import abc
  import json
  from ..typecheck import typecheck_method, sequenceof
  from ..utils.misc import escape_str
label_desc: Use image node_id 2 for calling the BlockMatrixPersistReader obj's underlying member method code with example usage: obj.render() and returns: escape_str