code: func PrintJoinedSemigraphics(screen tcell.Screen, x, y int, ch rune, color tcell.Color) {
  	previous, _, style, _ := screen.GetContent(x, y)
  	style = style.Foreground(color)
  
  	// What's the resulting rune?
  	var result rune
  	if ch == previous {
  		result = ch
  	} else {
  		if ch < previous {
  			previous, ch = ch, previous
  		}
  		result = SemigraphicJoints[string([]rune{previous, ch})]
  	}
  	if result == 0 {
  		result = ch
  	}
  
  	// We only print something if we have something.
  	screen.SetContent(x, y, result, nil, style)
  }
docs: // PrintJoinedSemigraphics prints a semigraphics rune into the screen at the given
  // position with the given color, joining it with any existing semigraphics
  // rune. Background colors are preserved. At this point, only regular single
  // line borders are supported.