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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 ghuser_role(name, rawtext, text, lineno, inliner, options={}, content=[]):
 """Link to a GitHub user. Returns 2 part tuple containing list of nodes to insert into the document and a list of system messages. Both are allowed to be empty. :param name: The role name used in the document. :param rawtext: The entire markup snippet, with role. :param text: The text marked with the role. :param lineno: The line number where rawtext appears in the input. :param inliner: The inliner instance that called us. :param options: Directive options for customization. :param content: The directive content for customization. """

    app = inliner.document.settings.env.app
    #app.info('user link %r' % text)
    ref = 'https://www.github.com/' + text
    node = nodes.reference(rawtext, text, refuri=ref, **options)
    return [node], []