class_docstr: Test docstring. 
class_docstr_tok: ["Test","docstring","."]
docstr: Remove old decision surface.
code: def remove_surface(self):
      """Remove old decision surface."""
      if len(self.contours) > 0:
          for contour in self.contours:
              if isinstance(contour, ContourSet):
                  for lineset in contour.collections:
                      lineset.remove()
              else:
                  contour.remove()
          self.contours = []
  
imports: from __future__ import division, print_function
  import matplotlib
  from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg
  from matplotlib.backends.backend_tkagg import NavigationToolbar2TkAgg
  from matplotlib.figure import Figure
  from matplotlib.contour import ContourSet
  import Tkinter
  import sys
  import numpy
  from sklearn import svm
  from sklearn.datasets import dump_svmlight_file
  from sklearn.externals.six.moves import xrange
label_desc: Use image node_id 8 for calling the View obj's underlying member method code with example usage: obj.remove_surface() without return types