def streams(self, stream_types=None, sorting_excludes=None):
        """Attempts to extract available streams.

        Returns a :class:`dict` containing the streams, where the key is
        the name of the stream, most commonly the quality and the value
        is a :class:`Stream` object.

        The result can contain the synonyms **best** and **worst** which
        points to the streams which are likely to be of highest and
        lowest quality respectively.

        If multiple streams with the same name are found, the order of
        streams specified in *stream_types* will determine which stream
        gets to keep the name while the rest will be renamed to
        "<name>_<stream type>".

        The synonyms can be fine tuned with the *sorting_excludes*
        parameter. This can be either of these types:

            - A list of filter expressions in the format
              *[operator]<value>*. For example the filter ">480p" will
              exclude streams ranked higher than "480p" from the list
              used in the synonyms ranking. Valid operators are >, >=, <
              and <=. If no operator is specified then equality will be
              tested.

            - A function that is passed to filter() with a list of
              stream names as input.


        :param stream_types: A list of stream types to return.
        :param sorting_excludes: Specify which streams to exclude from
                                 the best/worst synonyms.


        .. versionchanged:: 1.4.2
           Added *priority* parameter.

        .. versionchanged:: 1.5.0
           Renamed *priority* to *stream_types* and changed behaviour
           slightly.

        .. versionchanged:: 1.5.0
           Added *sorting_excludes* parameter.

        .. versionchanged:: 1.6.0
           *sorting_excludes* can now be a list of filter expressions
           or a function that is passed to filter().


        """

        try:
            ostreams = self._get_streams()
            if isinstance(ostreams, dict):
                ostreams = ostreams.items()

            # Flatten the iterator to a list so we can reuse it.
            if ostreams:
                ostreams = list(ostreams)
        except NoStreamsError:
            return {}
        except (IOError, OSError, __HOLE__) as err:
            raise PluginError(err)

        if not ostreams:
            return {}

        if stream_types is None:
            stream_types = self.default_stream_types(ostreams)

        # Add streams depending on stream type and priorities
        sorted_streams = sorted(iterate_streams(ostreams),
                                key=partial(stream_type_priority,
                                            stream_types))

        streams = {}
        for name, stream in sorted_streams:
            stream_type = type(stream).shortname()

            if stream_type not in stream_types:
                continue

            existing = streams.get(name)
            if existing:
                existing_stream_type = type(existing).shortname()
                if existing_stream_type != stream_type:
                    name = "{0}_{1}".format(name, stream_type)

                if name in streams:
                    name = "{0}_alt".format(name)
                    num_alts = len(list(filter(lambda n: n.startswith(name), streams.keys())))

                    # We shouldn't need more than 2 alt streams
                    if num_alts >= 2:
                        continue
                    elif num_alts > 0:
                        name = "{0}{1}".format(name, num_alts + 1)

            # Validate stream name and discard the stream if it's bad.
            match = re.match("([A-z0-9_+]+)", name)
            if match:
                name = match.group(1)
            else:
                self.logger.debug("The stream '{0}' has been ignored "
                                  "since it is badly named.", name)
                continue

            # Force lowercase name and replace space with underscore.
            streams[name.lower()] = stream

        # Create the best/worst synonmys
        stream_weight_only = lambda s: (self.stream_weight(s)[0] or
                                        (len(streams) == 1 and 1))
        stream_names = filter(stream_weight_only, streams.keys())
        sorted_streams = sorted(stream_names, key=stream_weight_only)

        if isinstance(sorting_excludes, list):
            for expr in sorting_excludes:
                filter_func = stream_sorting_filter(expr, self.stream_weight)
                sorted_streams = list(filter(filter_func, sorted_streams))
        elif callable(sorting_excludes):
            sorted_streams = list(filter(sorting_excludes, sorted_streams))

        if len(sorted_streams) > 0:
            best = sorted_streams[-1]
            worst = sorted_streams[0]
            streams["best"] = streams[best]
            streams["worst"] = streams[worst]

        return streams
dataset/ETHPy150Open chrippa/livestreamer/src/livestreamer/plugin/plugin.py/Plugin.streams