code: def __call__(self, mu):
      return mu**2 * (1 - mu) ** 2
  
file_path: statsmodels/examples/python/quasibinomial.py
imports: import statsmodels.api
  import numpy
  import pandas
  import matplotlib.pyplot
  from io import StringIO
label_desc: Use image node_id 1 for calling the vf obj's underlying member method code with example usage: obj.__call__(mu) and returns: unknown