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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 markdown_media_css():
 """ Add css requirements to HTML. :returns: Editor template context. """

    return dict(
        CSS_SET=posixpath.join(
            settings.MARKDOWN_SET_PATH, settings.MARKDOWN_SET_NAME, 'style.css'
        ),
        CSS_SKIN=posixpath.join(
            'django_markdown', 'skins', settings.MARKDOWN_EDITOR_SKIN,
            'style.css'
        )
    )