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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 relpath(dataset_uri, item_identifier):
 """Return relpath associated with the item. """

    dataset = dtoolcore.DataSet.from_uri(dataset_uri)
    try:
        props = dataset.item_properties(item_identifier)
    except KeyError:
        click.secho(
            "No such item in dataset: {}".format(item_identifier),
            fg="red",
            err=True
        )
        sys.exit(21)
    click.secho(props["relpath"])