class_docstr: Nested Conditional Logit (RUNMNL), data handling test
  
  unfinished, does not do anything yet
code: def loglike_branch(self, params, tau):
      # not yet sure how to keep track of branches during walking of tree
      ivs = []
      for b in branches:  # noqa:F821  See GH#5756
          probs, iv = self.loglike_leafbranch(params, tau)
          ivs.append(iv)
  
      # ivs = np.array(ivs)   #note ivs is (nobs,nbranchchoices)
      ivs = np.column_stack(ivs)  # this way ?
      exptiv = np.exp(tau * ivs)
      sumexptiv = exptiv.sum(1)
      logsumexpxb = np.log(sumexpxb)  # noqa:F821  See GH#5756
      probs = exptiv / sumexptiv[:, None]
  
file_path: statsmodels/statsmodels/sandbox/regression/runmnl.py
imports: import numpy
  import numpy.lib.recfunctions
  from scipy import optimize
label_desc: Use image node_id 4 for calling the TryNCLogit obj's underlying member method code with example usage: obj.loglike_branch(params, tau) without return types