code: func countColumns(node *blackfriday.Node) int {
  	var columns int
  
  	node.Walk(func(node *blackfriday.Node, entering bool) blackfriday.WalkStatus {
  		switch node.Type {
  		case blackfriday.TableRow:
  			if !entering {
  				return blackfriday.Terminate
  			}
  		case blackfriday.TableCell:
  			if entering {
  				columns++
  			}
  		default:
  		}
  		return blackfriday.GoToNext
  	})
  	return columns
  }
docs: // because roff format requires knowing the column count before outputting any table
  // data we need to walk a table tree and count the columns