code: func DrawVerticalLine(x, y, h int, r rune) {
  	x, y, _, h = clip(x, y, 1, h)
  	if h == 0 {
  		return
  	}
  
  	for i := y; i < y+h; i++ {
  		putCharUnsafe(x, i, r)
  	}
  }
docs: // DrawVerticalLine draws the part of the vertical line that is inside current
  // clipping rectangle