class_docstr: A parse tree node with a few extra methods.
class_docstr_tok: ["A","parse","tree","node","with","a","few","extra","methods","."]
code: def nice_explanation(self):
      return _format_explanation(self.explanation)
  
imports: import py
  import sys, inspect
  from compiler import parse, ast, pycodegen
  from py._code.assertion import BuiltinAssertionError, _format_explanation
  import types
label_desc: Use image node_id 4 for calling the Interpretable obj's underlying member method code with example usage: obj.nice_explanation() and returns: _format_explanation