code: def integrate_fluxes(self):
          
          fluxes = self.sequences.fluxes
          for flux in fluxes.numerics:
              points = getattr(fluxes.fastaccess, '_%s_points' % flux.name)
              coefs = self.numconsts.a_coefs[self.numvars.idx_method-1,
                                             self.numvars.idx_stage,
                                             :self.numvars.idx_method]
              flux(self.numvars.dt *
                   numpy.dot(coefs, points[:self.numvars.idx_method]))
docs: Perform a dot multiplication between the fluxes and the
          A coefficients associated with the different stages of the
          actual method.
  
          >>> from hydpy.models.test_v1 import *
          >>> parameterstep()
          >>> model.numvars.idx_method = 2
          >>> model.numvars.idx_stage = 1
          >>> model.numvars.dt = 0.5
          >>> points = numpy.asarray(fluxes.fastaccess._q_points)
          >>> points[:4] = 15., 2., -999., 0.
          >>> model.integrate_fluxes()
          >>> from hydpy import round_
          >>> from hydpy import pub
          >>> round_(numpy.asarray(model.numconsts.a_coefs)[1, 1, :2])
          0.375, 0.125
          >>> fluxes.q
          q(2.9375)