code: def set_dashes(self, offset, dashes):
      self._dashes = offset, dashes
      if dashes is None:
          self.ctx.set_dash([], 0)  # switch dashes off
      else:
          self.ctx.set_dash(
              list(self.renderer.points_to_pixels(np.asarray(dashes))),
              offset,
          )
  
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 9 for calling the GraphicsContextCairo obj's underlying member method code with example usage: obj.set_dashes(offset, dashes) without return types