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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _query_for_individual_audio(self, run, tag, sample, index):
 """Builds a URL for accessing the specified audio. This should be kept in sync with _serve_audio_metadata. Note that the URL is *not* guaranteed to always return the same audio, since audio may be unloaded from the reservoir as new audio entries come in. Args: run: The name of the run. tag: The tag. index: The index of the audio entry. Negative values are OK. Returns: A string representation of a URL that will load the index-th sampled audio in the given run with the given tag. """

    query_string = urllib.parse.urlencode({
        'run': run,
        'tag': tag,
        'sample': sample,
        'index': index,
    })
    return query_string