code: def hessian(self, params):
      from statsmodels.tools.numdiff import approx_fprime
  
      hess = approx_fprime(params, self.score)
      hess = np.atleast_2d(hess)
      return hess
  
imports: import numpy
  import statsmodels.base.model
  import statsmodels.regression.linear_model
  import statsmodels.base.wrapper
  from statsmodels.discrete.discrete_model import MultinomialResults, MultinomialResultsWrapper
  import collections
  import warnings
  import itertools
label_desc: Use image node_id 2 for calling the _ConditionalModel obj's underlying member method code with example usage: obj.hessian(params) and returns: hess