code: func checkValidity(cols []string, datas [][]string) bool {
  	colLen := len(cols)
  	if len(datas) == 0 || colLen == 0 {
  		return false
  	}
  
  	for _, data := range datas {
  		if colLen != len(data) {
  			return false
  		}
  	}
  
  	return true
  }
docs: // checkValidity checks whether cols and every data have the same length.