code: def set_joinstyle(self, js):
      if js in ("miter", "round", "bevel"):
          self._joinstyle = js
          self.ctx.set_line_join(self._joind[js])
      else:
          raise ValueError("Unrecognized join style.  Found %s" % js)
  
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import six
  import gzip
  import sys
  import warnings
  import numpy
  from matplotlib.backend_bases import _Backend, FigureCanvasBase, FigureManagerBase, GraphicsContextBase, RendererBase
  from matplotlib.mathtext import MathTextParser
  from matplotlib.path import Path
  from matplotlib.transforms import Affine2D
  from matplotlib.font_manager import ttfFontProperty
label_desc: Use image node_id 10 for calling the GraphicsContextCairo obj's underlying member method code with example usage: obj.set_joinstyle(js) without return types