code: def set_linewidth(self, w):
      self._linewidth = float(w)
      self.ctx.set_line_width(self.renderer.points_to_pixels(w))
  
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 13 for calling the GraphicsContextCairo obj's underlying member method code with example usage: obj.set_linewidth(w) without return types