code: def gendat_nested0():
      ns = Nested_simulator()
      ns.error_sd = 1.0
      ns.params = np.r_[0.0, 1, 1, -1, -1]
      ns.ngroups = 50
      ns.nest_sizes = [10, 5]
      ns.dep_params = [2.0, 1.0]
      ns.simulate()
      return ns, Nested(ns.id_matrix)
  
imports: from statsmodels.compat.python import lrange
  import scipy
  import numpy
  from itertools import product
  from statsmodels.genmod.families import Gaussian
  from statsmodels.genmod.generalized_estimating_equations import GEE
  from statsmodels.genmod.cov_struct import Autoregressive, Nested
label_desc: Use image node_id 3 for calling a global function with example usage: gendat_nested0() and returns: ns,  Nested