code: func (v *View) deleteRune(x, y int) error {
  	v.tainted = true
  
  	x, y, err := v.realPosition(x, y)
  	if err != nil {
  		return err
  	}
  
  	if x < 0 || y < 0 || y >= len(v.lines) || x >= len(v.lines[y]) {
  		return errors.New("invalid point")
  	}
  	v.lines[y] = append(v.lines[y][:x], v.lines[y][x+1:]...)
  	return nil
  }
docs: // deleteRune removes a rune from the view's internal buffer, at the
  // position corresponding to the point (x, y).