How to use the streamz.sources.Source function in streamz

line = self.file.read()
            if line:
                buffer = buffer + line
                if self.delimiter in buffer:
                    parts = buffer.split(self.delimiter)
                    buffer = parts.pop(-1)
                    for part in parts:
                        yield self._emit(part + self.delimiter)
            else:
                yield gen.sleep(self.poll_interval)
            if self.stopped:
                break


@Stream.register_api(staticmethod)
class filenames(Source):
    """ Stream over filenames in a directory

    Parameters
    ----------
    path: string
        Directory path or globstring over which to search for files
    poll_interval: Number
        Seconds between checking path
    start: bool (False)
        Whether to start running immediately; otherwise call stream.start()
        explicitly.

    Examples
    --------
    >>> source = Stream.filenames('path/to/dir')  # doctest: +SKIP
    >>> source = Stream.filenames('path/to/*.csv', poll_interval=0.500)  # doctest: +SKIP

while not self.stopped:
            self.started = True
            line = self.file.read()
            if line:
                buffer = buffer + line
                if self.delimiter in buffer:
                    parts = buffer.split(self.delimiter)
                    buffer = parts.pop(-1)
                    for part in parts:
                        yield self._emit(part + self.delimiter)
            else:
                yield gen.sleep(self.poll_interval)


@Stream.register_api(staticmethod)
class filenames(Source):
    """ Stream over filenames in a directory

    Parameters
    ----------
    path: string
        Directory path or globstring over which to search for files
    poll_interval: Number
        Seconds between checking path
    start: bool (False)
        Whether to start running immediately; otherwise call stream.start()
        explicitly.

    Examples
    --------
    >>> source = Stream.filenames('path/to/dir')  # doctest: +SKIP
    >>> source = Stream.filenames('path/to/*.csv', poll_interval=0.500)  # doctest: +SKIP

    @gen.coroutine
    def do_poll(self):
        while True:
            filenames = set(glob(self.path))
            new = filenames - self.seen
            for fn in sorted(new):
                self.seen.add(fn)
                yield self._emit(fn)
            yield gen.sleep(self.poll_interval)  # TODO: remove poll if delayed
            if self.stopped:
                break


@Stream.register_api(staticmethod)
class from_kafka(Source):
    """ Accepts messages from Kafka

    Uses the confluent-kafka library,
    https://docs.confluent.io/current/clients/confluent-kafka-python/


    Parameters
    ----------
    topics: list of str
        Labels of Kafka topics to consume from
    consumer_params: dict
        Settings to set up the stream, see
        https://docs.confluent.io/current/clients/confluent-kafka-python/#configuration
        https://github.com/edenhill/librdkafka/blob/master/CONFIGURATION.md
        Examples:
        bootstrap.servers: Connection string(s) (host:port) by which to reach Kafka

    @gen.coroutine
    def do_poll(self):
        while True:
            filenames = set(glob(self.path))
            new = filenames - self.seen
            for fn in sorted(new):
                self.seen.add(fn)
                yield self._emit(fn)
            yield gen.sleep(self.poll_interval)  # TODO: remove poll if delayed
            if self.stopped:
                break


@Stream.register_api(staticmethod)
class from_tcp(Source):
    """
    Creates events by reading from a socket using tornado TCPServer

    The stream of incoming bytes is split on a given delimiter, and the parts
    become the emitted events.

    Parameters
    ----------
    port : int
        The port to open and listen on. It only gets opened when the source
        is started, and closed upon ``stop()``
    delimiter : bytes
        The incoming data will be split on this value. The resulting events
        will still have the delimiter at the end.
    start : bool
        Whether to immediately initiate the source. You probably want to

process.proc.terminate()

    def start(self):
        """Start external process"""
        if self.stopped:
            self.loop.add_callback(self._start_process)
            self.stopped = False

    def stop(self):
        """Shutdown external process"""
        if not self.stopped:
            self.stopped = True


@Stream.register_api(staticmethod)
class from_kafka(Source):
    """ Accepts messages from Kafka

    Uses the confluent-kafka library,
    https://docs.confluent.io/current/clients/confluent-kafka-python/


    Parameters
    ----------
    topics: list of str
        Labels of Kafka topics to consume from
    consumer_params: dict
        Settings to set up the stream, see
        https://docs.confluent.io/current/clients/confluent-kafka-python/#configuration
        https://github.com/edenhill/librdkafka/blob/master/CONFIGURATION.md
        Examples:
        bootstrap.servers, Connection string(s) (host:port) by which to reach

def start(self):
        """Start HTTP server and listen"""
        if self.stopped:
            self.loop.add_callback(self._start_server)
            self.stopped = False

    def stop(self):
        """Shutdown HTTP server"""
        if not self.stopped:
            self.server.stop()
            self.server = None
            self.stopped = True


@Stream.register_api(staticmethod)
class from_process(Source):
    """Messages from a running external process

    This doesn't work on Windows

    Parameters
    ----------
    cmd : list of str or str
        Command to run: program name, followed by arguments
    open_kwargs : dict
        To pass on the the process open function, see ``subprocess.Popen``.
    with_stderr : bool
        Whether to include the process STDERR in the stream
    start : bool
        Whether to immediately startup the process. Usually you want to connect
        downstream nodes first, and then call ``.start()``.

class Source(Stream):
    _graphviz_shape = 'doubleoctagon'

    def __init__(self, **kwargs):
        self.stopped = True
        super(Source, self).__init__(**kwargs)

    def stop(self):  # pragma: no cover
        # fallback stop method - for poll functions with while not self.stopped
        if not self.stopped:
            self.stopped = True


@Stream.register_api(staticmethod)
class from_textfile(Source):
    """ Stream data from a text file

    Parameters
    ----------
    f: file or string
        Source of the data. If string, will be opened.
    poll_interval: Number
        Interval to poll file for new data in seconds
    delimiter: str
        Character(s) to use to split the data into parts
    start: bool
        Whether to start running immediately; otherwise call stream.start()
        explicitly.
    from_end: bool
        Whether to begin streaming from the end of the file (i.e., only emit
        lines appended after the stream starts).

def write(text):
        file.write(prefix + text + suffix)
        if flush:
            file.flush()

    upstream.sink(write)
    return file


class Source(Stream):
    _graphviz_shape = 'doubleoctagon'


@Stream.register_api(staticmethod)
class from_textfile(Source):
    """ Stream data from a text file

    Parameters
    ----------
    f: file or string
    poll_interval: Number
        Interval to poll file for new data in seconds
    delimiter: str ("\n")
        Character(s) to use to split the data into parts
    start: bool (False)
        Whether to start running immediately; otherwise call stream.start()
        explicitly.

    Example
    -------
    >>> source = Stream.from_textfile('myfile.json')  # doctest: +SKIP

def __init__(self, **kwargs):
        self.stopped = True
        super(Source, self).__init__(**kwargs)

self.server.listen(self.port)

    def start(self):
        if self.stopped:
            self.loop.add_callback(self._start_server)
            self.stopped = False

    def stop(self):
        if not self.stopped:
            self.server.stop()
            self.server = None
            self.stopped = True


@Stream.register_api(staticmethod)
class from_http_server(Source):
    """Listen for HTTP POSTs on given port

    Each connection will emit one event, containing the body data of
    the request

    Parameters
    ----------
    port : int
        The port to listen on
    path : str
        Specific path to listen on. Can be regex, but content is not used.
    start : bool
        Whether to immediately startup the server. Usually you want to connect
        downstream nodes first, and then call ``.start()``.
    server_kwargs : dict or None
        If given, set of further parameters to pass on to HTTPServer