code: func isTemporalColumn(expr Expression) bool {
  	ft := expr.GetType()
  	if _, isCol := expr.(*Column); !isCol {
  		return false
  	}
  	if !types.IsTypeTime(ft.Tp) && ft.Tp != mysql.TypeDuration {
  		return false
  	}
  	return true
  }
docs: // isTemporalColumn checks if a expression is a temporal column,
  // temporal column indicates time column or duration column.