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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 bolditalic(name, rawtext, text, lineno, inliner, options={}, content=[]):
 """ Add bolditalic role. 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 this function. :param options: Directive options for customization. :param content: The directive content for customization. """

    node = nodes.inline(rawtext, text)
    node.set_class('bolditalic')
    return [node], []