class_docstr: Initializes a Bayesian Network.
  A models stores nodes and edges with conditional probability
  distribution (cpd) and other attributes.
  
  models hold directed edges.  Self loops are not allowed neither
  multiple (parallel) edges.
  
  Nodes can be any hashable python object.
  
  Edges are represented as links between nodes.
  
  Parameters
  ----------
  ebunch: input graph
      Data to initialize graph.  If ebunch=None (default) an empty
      graph is created.  The ebunch can be an edge list, or any
      NetworkX graph object.
  
  latents: list, array-like
      List of variables which are latent (i.e. unobserved) in the model.
  
  Examples
  --------
  Create an empty Bayesian Network with no nodes and no edges.
  
  >>> from pgmpy.models import BayesianNetwork
  >>> G = BayesianNetwork()
  
  G can be grown in several ways.
  
  **Nodes:**
  
  Add one node at a time:
  
  >>> G.add_node('a')
  
  Add the nodes from any container (a list, set or tuple or the nodes
  from another graph).
  
  >>> G.add_nodes_from(['a', 'b'])
  
  **Edges:**
  
  G can also be grown by adding edges.
  
  Add one edge,
  
  >>> G.add_edge('a', 'b')
  
  a list of edges,
  
  >>> G.add_edges_from([('a', 'b'), ('b', 'c')])
  
  If some edges connect nodes not yet in the model, the nodes
  are added automatically.  There are no errors when adding
  nodes or edges that already exist.
  
  **Shortcuts:**
  
  Many common graph features allow python syntax for speed reporting.
  
  >>> 'a' in G     # check if node in graph
  True
  >>> len(G)  # number of nodes in graph
  3
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docstr: Returns a dictionary mapping each node to its list of possible states.
  
  Returns
  -------
  state_dict: dict
      Dictionary of nodes to possible states
code: def states(self):
      """
      Returns a dictionary mapping each node to its list of possible states.
  
      Returns
      -------
      state_dict: dict
          Dictionary of nodes to possible states
      """
      state_names_list = [cpd.state_names for cpd in self.cpds]
      state_dict = {
          node: states
          for d in state_names_list
          for node, states in d.items()
      }
      return state_dict
  
imports: import itertools
  from collections import defaultdict
  from functools import reduce
  from operator import mul
  import networkx
  import numpy
  import pandas
  from joblib import Parallel, delayed
  from tqdm.auto import tqdm
  from pgmpy.base import DAG
  from pgmpy.factors.continuous import ContinuousFactor
  from pgmpy.factors.discrete import DiscreteFactor, JointProbabilityDistribution, TabularCPD
  from pgmpy.global_vars import logger
  from pgmpy.models.MarkovNetwork import MarkovNetwork
  from pgmpy.utils import compat_fns
label_desc: Use image node_id 9 for calling the BayesianNetwork obj's underlying member method code with example usage: obj.states() and returns: state_dict