code: def time_range(self,flag=None):
          '''
          time range of the current dataset
          
          :keyword flag: use a flag array to know the time range of an indexed slice of the object
          '''
          if self.count==0: return [[None,None],[None,None]]
          
          if flag is None : return cnes_convert([self.date.min(),self.date.max()])
          else : return cnes_convert([self.date.compress(flag).min(),self.date.compress(flag).max()]f time_range(self,flag=None):
          '''
          time range of the current dataset
          
          :keyword flag: use a flag array to know the time range of an indexed slice of the object
          '''
          if self.count==0: return [[None,None],[None,None]]
          
          if flag is None : return cnes_convert([self.date.min(),self.date.max()])
          else : return cnes_convert([self.date.compress(flag).min(),self.date.compress(flag).max()])
docs: time range of the current dataset
          
          :keyword flag: use a flag array to know the time range of an indexed slice of the object