class_docstr: Class for representing Structural Equation Models. This class is a wrapper over
  `SEMGraph` and `SEMAlg` to provide a consistent API over the different representations.
  
  Attributes
  ----------
  model: SEMGraph instance
      A graphical representation of the model.
class_docstr_tok: ["Class","for","representing","Structural","Equation","Models",".","This","class","is","a","wrapper","over","`","SEMGraph","`","and","`","SEMAlg","`","to","provide","a","consistent","API","over","the","different","representations",".","Attributes","--","--","--","--","--","model",":","SEMGraph","instance","A","graphical","representation","of","the","model","."]
code: def fit(self):
      pass
  
imports: import itertools
  import networkx
  import numpy
  import pandas
  from networkx.algorithms.dag import descendants
  from pyparsing import OneOrMore, Optional, Suppress, Word, alphanums, nums
  from pgmpy.base import DAG
  from pgmpy.global_vars import logger
label_desc: Use image node_id 6 for calling the SEM obj's underlying member method code with example usage: obj.fit() without return types