code: func Position(blk Block) Pos {
  	switch blk := blk.(type) {
  	case *TextBlock:
  		return blk.Pos
  	case *CodeBlock:
  		return blk.Pos
  	case *PrintBlock:
  		return blk.Pos
  	case *RawPrintBlock:
  		return blk.Pos
  	case *ComponentStartBlock:
  		return blk.Pos
  	case *ComponentEndBlock:
  		return blk.Pos
  	case *AttrStartBlock:
  		return blk.Pos
  	case *AttrEndBlock:
  		return blk.Pos
  	default:
  		panic("unreachable")
  	}
  }
docs: // Position returns the position of the block.