code: def add_example(self, x, y, label):
      self.model.data.append((x, y, label))
      self.model.changed("example_added")
  
      # update decision surface if already fitted.
      self.refit()
  
imports: import matplotlib
  from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg
  import sys
  import tkinter
  import numpy
  from matplotlib.contour import ContourSet
  from matplotlib.figure import Figure
  from sklearn import svm
  from sklearn.datasets import dump_svmlight_file
label_desc: Use image node_id 5 for calling the Controller obj's underlying member method code with example usage: obj.add_example(x, y, label) without return types