code: def update(self):
          
          con = self.subpars.pars.control
          self(con.ft*1000./self.simulationstep.seconds)
docs: Update |QFactor| based on |FT| and the current simulation step size.
  
          >>> from hydpy.models.lland import *
          >>> parameterstep('1d')
          >>> simulationstep('1d')
          >>> ft(10.0)
          >>> derived.qfactor.update()
          >>> derived.qfactor
          qfactor(0.115741)