def upload(self, filename, **kwargs):
        kwargs['index'] = self.name
        path = 'data/inputs/oneshot'
        self.service.post(path, name=filename, **kwargs)
        return self
`relative_to` is the name of a sibling value that is
dataset/ETHPy150Open hvandenb/splunk-elasticsearch/search-elasticsearch/bin/splunklib/client.py/Index.upload--crossover with--dataset/ETHPy150Open beetbox/beets/beets/util/confit.py/Filename.__init__