code: def trim(self, lower=None, upper=None):
          
          whc = self.subseqs.seqs.model.parameters.control.whc
          wc = self.subseqs.wc
          if lower is None:
              if wc.values is not None:
                  with numpy.errstate(divide='ignore', invalid='ignore'):
                      lower = numpy.clip(wc.values / whc.values, 0., numpy.inf)
              else:
                  lower = 0.
          hland_sequences.State1DSequence.trim(self, lower, upper)
docs: Trim values in accordance with :math:`WC \\leq WHC \\cdot SP`.
  
          >>> from hydpy.models.hland import *
          >>> parameterstep('1d')
          >>> nmbzones(7)
          >>> whc(0.1)
          >>> states.wc.values = -1.0, 0.0, 1.0, -1.0, 0.0, 0.5, 1.0
          >>> states.sp(-1., 0., 0., 5., 5., 5., 5.)
          >>> states.sp
          sp(0.0, 0.0, 10.0, 5.0, 5.0, 5.0, 10.0)