code: def index(self):
          
          import ibis.expr.operations as ops
  
          return ops.DayOfWeekIndex(self.op().arg).to_expr()
docs: Get the index of the day of the week.
  
          Returns
          -------
          IntegerValue
              The index of the day of the week. Ibis follows pandas conventions,
              where **Monday = 0 and Sunday = 6**.