def fetch(page=None, article=None):
    """Fetch the context from external source for page. Some times, if
        more than one article is present for a page, then instead of using
        ``page`` keyword, supply the ``article`` keyword.

        ``page``,
            an instance of class :class:`Page`. Contains page description and
            its context gathered so far.

        ``article``,
            a tuple of article content and metadata, refer to :class:`Page`
            for exact detail.

        Return a python dictionary of context attributes. Context must contain
        basic python data-types like integers, float, string, list, tuple,
        dictionary.
        """
