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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 output_notebook( d3js_url="//d3js.org/d3.v3.min", requirejs_url="//cdnjs.cloudflare.com/ajax/libs/require.js/2.1.10/require.min.js", html_template=None ):
 """ Import required Javascript libraries to Jupyter Notebook. """


    if html_template is None:
        html_template = read_lib('html', 'setup')

    setup_html = populate_template(
        html_template,
        d3js=d3js_url,
        requirejs=requirejs_url
    )

    display_html(setup_html)
    return