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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 get_sources(self, prefix=''):
 """ Retrieve a set of absolute paths to sources, according to `prefix` `ConfigParser` will perform wildcard expansion and filtering. Args: prefix: str, the desired prefix. Returns: utils.utils.OrderedSet: The set of sources for the given `prefix`. """

        prefix = prefix.replace('-', '_')
        prefixed = '%s_sources' % prefix

        if prefixed in self.__cli:
            sources = self.__cli.get(prefixed)
            from_conf = False
        else:
            sources = self.__config.get(prefixed)
            from_conf = True

        if sources is None:
            return OrderedSet()

        sources = self.__resolve_patterns(sources, from_conf)

        prefixed = '%s_source_filters' % prefix
        if prefixed in self.__cli:
            filters = self.__cli.get(prefixed)
            from_conf = False
        else:
            filters = self.__config.get(prefixed)
            from_conf = True

        if filters is None:
            return sources

        sources -= self.__resolve_patterns(filters, from_conf)

        return sources