remember(chain=-1, trace_index = randint(trace length to date))

        Sets the value of all tracing variables to a value recorded in
        their traces.

def remember(self, chain=-1, trace_index=None):
        """
        remember(chain=-1, trace_index = randint(trace length to date))

        Sets the value of all tracing variables to a value recorded in
        their traces.
        """
        if trace_index is None:
            trace_index = randint(self._cur_trace_index)

        for variable in self._variables_to_tally:
            if isinstance(variable, Stochastic):
                try:
                    variable.value = self.trace(
                        variable.__name__,
                        chain=chain)[trace_index]
                except:
                    cls, inst, tb = sys.exc_info()
                    warnings.warn(
                        'Unable to remember value of variable %s. Original error: \n\n%s: %s' %
                        (variable, cls.__name__, inst.message))