class_docstr: A "buffered" filter pen that accumulates contour data, passes
  it through a ``filterContour`` method when the contour is closed or ended,
  and finally draws the result with the output pen.
  
  Components are passed through unchanged.
code: def _flushContour(self):
      result = self.filterContour(self.value)
      if result is not None:
          self.value = result
      self.replay(self._outPen)
      self.value = []
  
imports: from fontTools.pens.basePen import AbstractPen
  from fontTools.pens.pointPen import AbstractPointPen
  from fontTools.pens.recordingPen import RecordingPen
label_desc: Use image node_id 4 for calling the ContourFilterPen obj's underlying member method code with example usage: obj._flushContour() without return types