code: def three_var_approx_single_group_mf(three_var_model):
      return MeanField(model=three_var_model)
  
imports: import functools
  import numpy
  import pytensor.tensor
  import pytest
  import pymc
  from pymc.variational import opvi
  from pymc.variational.approximations import Empirical, EmpiricalGroup, FullRank, FullRankGroup, MeanField, MeanFieldGroup
  from tests.helpers import not_raises
label_desc: Use image node_id 9 for calling a global function with example usage: three_var_approx_single_group_mf(three_var_model) and returns: MeanField