code: def set_foreground(self, fg, isRGBA=None):
          
          # Implementation note: wxPython has a separate concept of pen and
          # brush - the brush fills any outline trace left by the pen.
          # Here we set both to the same colour - if a figure is not to be
          # filled, the renderer will set the brush to be transparent
          # Same goes for text foreground...
          DEBUG_MSG("set_foreground()", 1, self)
          self.select()
          GraphicsContextBase.set_foreground(self, fg, isRGBA)
  
          self._pen.SetColour(self.get_wxcolour(self.get_rgb()))
          self.gfx_ctx.SetPen(self._pen)
          self.unselect()
docs: Set the foreground color.  fg can be a matlab format string, a
          html hex color string, an rgb unit tuple, or a float between 0
          and 1.  In the latter case, grayscale is used.