Show the content of a specific overlay.

def show(dataset_uri, overlay_name):
    """
    Show the content of a specific overlay.
    """
    dataset = dtoolcore.DataSet.from_uri(dataset_uri)
    try:
        overlay = dataset.get_overlay(overlay_name)
    except:  # NOQA
        click.secho(
            "No such overlay: {}".format(overlay_name),
            fg="red",
            err=True
        )
        sys.exit(11)

    formatted_json = json.dumps(overlay, indent=2)
    colorful_json = pygments.highlight(
        formatted_json,
        pygments.lexers.JsonLexer(),
        pygments.formatters.TerminalFormatter())
    click.secho(colorful_json, nl=False)