class_docstr: Helper class to check whether the plotter's rendered content has changed
  since the last call.
class_docstr_tok: ["Helper","class","to","check","whether","the","plotter","'s","rendered","content","has","changed","since","the","last","call","."]
code: def _capture(self):
      self._plotter.show(auto_close=False)
      return self._plotter.screenshot()
  
imports: import itertools
  import platform
  import weakref
  import numpy
  import pytest
  from vtkmodules.vtkRenderingContext2D import vtkPen
  import pyvista
  from pyvista import examples
  from pyvista.plotting import charts
  from pyvista.plotting.colors import COLOR_SCHEMES
label_desc: Use image node_id 2 for calling the PlotterChanged obj's underlying member method code with example usage: obj._capture() and returns: self