def _dataslice(self, data, indices):
        if isinstance(data, Dimensioned) and indices:
            return data[indices]
        elif len(indices) > 0:
            self.warning('Cannot index into data element, extra data'
                         ' indices ignored.')
        return data
Performs a head request against a signed url to check for read access.
dataset/ETHPy150Open ioam/holoviews/holoviews/core/ndmapping.py/MultiDimensionalMapping._dataslice--crossover with--dataset/ETHPy150Open GoogleCloudPlatform/gsutil/gslib/commands/signurl.py/UrlSignCommand._ProbeObjectAccessWithClient