How to use the bbopt.examples.__init__._coconut.len function in bbopt

def __call__(self, *args, **kwargs):
        callargs = []
        argind = 0
        for i in _coconut.range(self._arglen):
            if i in self._argdict:
                callargs.append(self._argdict[i])
            elif argind >= _coconut.len(args):
                raise _coconut.TypeError("expected at least " + _coconut.str(self._arglen - _coconut.len(self._argdict)) + " argument(s) to " + _coconut.repr(self))
            else:
                callargs.append(args[argind])
                argind += 1
        callargs += self._stargs
        callargs += args[argind:]
        kwargs.update(self.keywords)
        return self.func(*callargs, **kwargs)
    def __repr__(self):

def __len__(self):
        return _coconut.len(self.iter)
    def __repr__(self):

def __len__(self):
            return _coconut.len(self._xrange)
        def __contains__(self, elem):

def __len__(self):
        return _coconut.min(_coconut.len(i) for i in self.iters)
    def __repr__(self):

def __call__(self, *args, **kwargs):
        callargs = []
        argind = 0
        for i in _coconut.range(self._arglen):
            if i in self._argdict:
                callargs.append(self._argdict[i])
            elif argind >= _coconut.len(args):
                raise _coconut.TypeError("expected at least " + _coconut.str(self._arglen - _coconut.len(self._argdict)) + " argument(s) to " + _coconut.repr(self))
            else:
                callargs.append(args[argind])
                argind += 1
        callargs += self._stargs
        callargs += args[argind:]
        kwargs.update(self.keywords)
        return self.func(*callargs, **kwargs)
    def __repr__(self):

def __len__(self):
        return _coconut.len(self.iter)
    def __repr__(self):

def index(self, elem):
        """Find the index of elem in the reversed iterator."""
        return _coconut.len(self.iter) - self.iter.index(elem) - 1
    def __fmap__(self, func):

def __len__(self):
        return _coconut.len(self.iter)
    def __repr__(self):