code: def addup_fluxes(self):
          
          fluxes = self.sequences.fluxes
          for flux in fluxes.numerics:
              sum_ = getattr(fluxes.fastaccess, '_%s_sum' % flux.name)
              sum_ += flux
              if flux.NDIM == 0:
                  setattr(fluxes.fastaccess, '_%s_sum' % flux.name, sum_)
docs: Add up the sum of the fluxes calculated so far.
  
          >>> from hydpy.models.test_v1 import *
          >>> parameterstep()
          >>> fluxes.fastaccess._q_sum = 1.0
          >>> fluxes.q(2.0)
          >>> model.addup_fluxes()
          >>> fluxes.fastaccess._q_sum
          3.0