code: def update(self):
          
          con = self.subpars.pars.control
          self(con.eqd1*con.tind)
docs: Update |KD1| based on |EQD1| and |TInd|.
  
          >>> from hydpy.models.lland import *
          >>> parameterstep('1d')
          >>> eqd1(0.5)
          >>> tind.value = 10.0
          >>> derived.kd1.update()
          >>> derived.kd1
          kd1(5.0)