code: def print_png(self, fobj):
      self._get_printed_image_surface().write_to_png(fobj)
  
imports: import functools
  import gzip
  import math
  import numpy
  from ..None import _api, cbook, font_manager
  from matplotlib.backend_bases import _Backend, FigureCanvasBase, FigureManagerBase, GraphicsContextBase, RendererBase
  from matplotlib.font_manager import ttfFontProperty
  from matplotlib.path import Path
  from matplotlib.transforms import Affine2D
label_desc: Use image node_id 5 for calling the FigureCanvasCairo obj's underlying member method code with example usage: obj.print_png(fobj) without return types