class_docstr: pass a custom callback function
  
  This makes sure it's being used.
class_docstr_tok: ["pass","a","custom","callback","function","This","makes","sure","it","'s","being","used","."]
code: def __init__(self):
      self.been_called = False
      self.ncalls = 0
  
imports: from __future__ import division, print_function, absolute_import
  import pytest
  from numpy.testing import assert_, assert_array_almost_equal, assert_allclose, assert_equal
  from pytest import raises
  import numpy
  from scipy.optimize import fmin_slsqp, minimize, NonlinearConstraint, Bounds
label_desc: Use image node_id 1 to create a new MyCallBack object from inherited base classes: object with example: obj = MyCallBack()