code: def set_joinstyle(self, js):
          
          DEBUG_MSG("set_joinstyle()", 1, self)
          self.select()
          GraphicsContextBase.set_joinstyle(self, js)
          self._pen.SetJoin(GraphicsContextWx._joind[self._joinstyle])
          self.gfx_ctx.SetPen(self._pen)
          self.unselect()
docs: Set the join style to be one of ('miter', 'round', 'bevel')