code: def set_border(self, thickness, color="black"):
          
          self._set_tk_config("highlightthickness", thickness)
          self._set_tk_config("highlightbackground", utils.convert_color(color))
docs: Sets the border thickness and color.
  
          :param int thickness:
              The thickenss of the border.
  
          :param str color:
              The color of the border.