code: def _initialize(self, funs_to_tally, length=None):
          
  
          for name, fun in six.iteritems(funs_to_tally):
              if name not in self._traces:
                  self._traces[
                      name] = self.__Trace__(
                          name=name,
                          getfunc=fun,
                          db=self)
  
              self._traces[name]._initialize(self.chains, length)
  
          self.trace_names.append(list(funs_to_tally.keys()))
  
          self.chains += 1
docs: Initialize the tallyable objects.
  
          Makes sure a Trace object exists for each variable and then initialize
          the Traces.
  
          :Parameters:
          funs_to_tally : dict
            Name- function pairs.
          length : int
            The expected length of the chain. Some database may need the argument
            to preallocate memory.