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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 _proc_accept_header(self, request, result):
 """ Process the Accept header rules for the request. Both the desired API version and content type can be determined from those rules. :param request: The Request object provided by WebOb. :param result: The Result object to store the results in. """


        if result:
            # Result has already been fully determined
            return

        try:
            accept = request.headers['accept']
        except KeyError:
            # No Accept header to examine
            return

        # Obtain the best-match content type and its parameters
        ctype, params = best_match(accept, self.types.keys())

        # Is it a recognized content type?
        if ctype not in self.types:
            return

        # Get the mapped ctype and version
        mapped_ctype, mapped_version = self.types[ctype](params)

        # Set the content type and version
        if mapped_ctype:
            result.set_ctype(mapped_ctype, ctype)
        if mapped_version:
            result.set_version(mapped_version)