code: def parentless_cpd() -> pd.DataFrame:
      """Create a (valid) CPD table for a parentless node"""
      df = pd.DataFrame([[0.3], [0.7]], index=[False, True])
      df.index.name = "e"
      return df
  
imports: import itertools
  from typing import Dict
  import numpy
  import pandas
  import pytest
  from pgmpy.models import BayesianNetwork
  from sklearn.datasets import load_iris
  from causalnex.discretiser import Discretiser
  from causalnex.network import BayesianNetwork
  from causalnex.structure import StructureModel
  from causalnex.structure.notears import from_pandas
label_desc: Use image node_id 20 for calling a global function with example usage: parentless_cpd() and returns: df