def _is_a(self, x):
        """
        Check if a Sage object ``x`` belongs to ``self``.

        This methods is a helper for :meth:`__contains__` and the
        constructor :meth:`_element_constructor_`.

        EXAMPLES::

            sage: U4 = DisjointUnionEnumeratedSets(
            ....:          Family(NonNegativeIntegers(), Compositions))
            sage: U4._is_a(Composition([3,2,1,1]))
            doctest:...: UserWarning: Disjoint union of Lazy family (<class 'sage.combinat.composition.Compositions'>(i))_{i in Non negative integers} is an infinite union
            The default implementation of __contains__ can loop forever. Please overload it.
            True
        """
        if self._keepkey:
            return (isinstance(x, tuple) and
                    x[0] in self._family.keys() and
                    x[1] in self._family[x[0]])
        else:
            from warnings import warn
            if self._family.cardinality() == Infinity:
                warn("%s is an infinite union\nThe default implementation of __contains__ can loop forever. Please overload it."%(self))
            return any(x in a for a in self._family)

    def serialize(v):
        global _have_warned_about_timestamps
        try:
            converted = calendar.timegm(v.utctimetuple())
            converted = converted * 1e3 + getattr(v, 'microsecond', 0) / 1e3
        except AttributeError:
            # Ints and floats are valid timestamps too
            if type(v) not in _number_types:
                raise TypeError('DateType arguments must be a datetime or timestamp')

            if not _have_warned_about_timestamps:
                _have_warned_about_timestamps = True
                warnings.warn("timestamp columns in Cassandra hold a number of "
                    "milliseconds since the unix epoch.  Currently, when executing "
                    "prepared statements, this driver multiplies timestamp "
                    "values by 1000 so that the result of time.time() "
                    "can be used directly.  However, the driver cannot "
                    "match this behavior for non-prepared statements, "
                    "so the 2.0 version of the driver will no longer multiply "
                    "timestamps by 1000.  It is suggested that you simply use "
                    "datetime.datetime objects for 'timestamp' values to avoid "
                    "any ambiguity and to guarantee a smooth upgrade of the "
                    "driver.")
            converted = v * 1e3

        return int64_pack(long(converted))

def tcp_server(listensocket, server, *args, **kw):
    """
    Given a socket, accept connections forever, spawning greenlets
    and executing *server* for each new incoming connection.
    When *listensocket* is closed, the ``tcp_server()`` greenlet will end.

    listensocket
        The socket from which to accept connections.
    server
        The callable to call when a new connection is made.
    \*args
        The positional arguments to pass to *server*.
    \*\*kw
        The keyword arguments to pass to *server*.
    """
    import warnings
    warnings.warn("gevent.socket.tcp_server is deprecated", DeprecationWarning, stacklevel=2)
    try:
        try:
            while True:
                client_socket = listensocket.accept()
                spawn_raw(server, client_socket, *args, **kw)
        except error, e:
            # Broken pipe means it was shutdown
            if e[0] != 32:
                raise
    finally:
        listensocket.close()

    def __init__(self, filepath, monitor='val_loss', verbose=0,
                 save_best_only=False, mode='auto'):

        super(Callback, self).__init__()
        self.monitor = monitor
        self.verbose = verbose
        self.filepath = filepath
        self.save_best_only = save_best_only

        if mode not in ['auto', 'min', 'max']:
            warnings.warn('ModelCheckpoint mode %s is unknown, '
                          'fallback to auto mode.' % (mode),
                          RuntimeWarning)
            mode = 'auto'

        if mode == 'min':
            self.monitor_op = np.less
            self.best = np.Inf
        elif mode == 'max':
            self.monitor_op = np.greater
            self.best = -np.Inf
        else:
            if 'acc' in self.monitor:
                self.monitor_op = np.greater
                self.best = -np.Inf
            else:
                self.monitor_op = np.less
                self.best = np.Inf

 def __init__(self, address, *, prefix=b'',
              RE=None, zmq=None, serializer=pickle.dumps):
     if RE is not None:
         warnings.warn("The RE argument to Publisher is deprecated and "
                       "will be removed in a future release of bluesky. "
                       "Update your code to subscribe this Publisher "
                       "instance to (and, if needed, unsubscribe from) to "
                       "the RunEngine manually.")
     if isinstance(prefix, str):
         raise ValueError("prefix must be bytes, not string")
     if b' ' in prefix:
         raise ValueError("prefix {!r} may not contain b' '".format(prefix))
     if zmq is None:
         import zmq
     if isinstance(address, str):
         address = address.split(':', maxsplit=1)
     self.address = (address[0], int(address[1]))
     self.RE = RE
     url = "tcp://%s:%d" % self.address
     self._prefix = bytes(prefix)
     self._context = zmq.Context()
     self._socket = self._context.socket(zmq.PUB)
     self._socket.connect(url)
     if RE:
         self._subscription_token = RE.subscribe(self)
     self._serializer = serializer

def mean_scaling(Y, axis=0):
    """Scaling of the data to have percent of baseline change along the
    specified axis

    Parameters
    ----------
    Y : array of shape (n_time_points, n_voxels)
       The input data.

    Returns
    -------
    Y : array of shape (n_time_points, n_voxels),
       The data after mean-scaling, de-meaning and multiplication by 100.

    mean : array of shape (n_voxels,)
        The data mean.
    """
    mean = Y.mean(axis=axis)
    if (mean == 0).any():
        warn('Mean values of 0 observed.'
             'The data have probably been centered.'
             'Scaling might not work as expected')
    mean = np.maximum(mean, 1)
    Y = 100 * (Y / mean - 1)
    return Y, mean

def TH2_to_FITS(hist, flipx=True):
    """Convert ROOT 2D histogram to FITS format.

    Parameters
    ----------
    hist : ROOT.TH2
        2-dim ROOT histogram

    Returns
    -------
    hdu : `~astropy.io.fits.ImageHDU`
        Histogram in FITS format.

    Examples
    --------
    >>> import ROOT
    >>> from gammapy.utils.root import TH2_to_FITS
    >>> root_hist = ROOT.TH2F()
    >>> fits_hdu = TH2_to_FITS(root_hist)
    >>> fits_hdu.writetofits('my_image.fits')
    """
    header = TH2_to_FITS_header(hist, flipx)
    if header['CDELT1'] > 0:
        warnings.warn('CDELT1 > 0 might not be handled properly.'
                      'A TH2 representing an astro image should have '
                      'a reversed x-axis, i.e. xlow > xhi')
    data = TH2_to_FITS_data(hist, flipx)
    hdu = fits.ImageHDU(data=data, header=header)
    return hdu

 def train(self, features, labels, normalisedlabels=False):
     idxs = self.selector(features, labels)
     if len(idxs) == 0:
         import warnings
         warnings.warn('milk.featureselection: No features selected! Using all features as fall-back.')
         idxs = np.arange(len(features[0]))
     return filterfeatures(idxs)

 def Window_(self, **criteria):
     warnings.warn(
         "WindowSpecification.Window() WindowSpecification.Window_(), "
         "WindowSpecification.window() and WindowSpecification.window_() "
         "are deprecated, please switch to WindowSpecification.ChildWindow()",
         DeprecationWarning)
     return self.ChildWindow(**criteria)

def column_or_1d(y, warn=False):
    """ Ravel column or 1d numpy array, else raises an error

    Parameters
    ----------
    y : array-like

    warn : boolean, default False
       To control display of warnings.

    Returns
    -------
    y : array

    """
    shape = np.shape(y)
    if len(shape) == 1:
        return np.ravel(y)
    if len(shape) == 2 and shape[1] == 1:
        if warn:
            warnings.warn("A column-vector y was passed when a 1d array was"
                          " expected. Please change the shape of y to "
                          "(n_samples, ), for example using ravel().",
                          DataConversionWarning, stacklevel=2)
        return np.ravel(y)

    raise ValueError("bad input shape {0}".format(shape))

    def __init__(self, unit="ns", tz=None):
        if isinstance(unit, DatetimeTZDtype):
            unit, tz = unit.unit, unit.tz

        if unit != 'ns':
            if isinstance(unit, str) and tz is None:
                # maybe a string like datetime64[ns, tz], which we support for
                # now.
                result = type(self).construct_from_string(unit)
                unit = result.unit
                tz = result.tz
                msg = (
                    "Passing a dtype alias like 'datetime64[ns, {tz}]' "
                    "to DatetimeTZDtype is deprecated. Use "
                    "'DatetimeTZDtype.construct_from_string()' instead."
                )
                warnings.warn(msg.format(tz=tz), FutureWarning, stacklevel=2)
            else:
                raise ValueError("DatetimeTZDtype only supports ns units")

        if tz:
            tz = timezones.maybe_get_tz(tz)
            tz = timezones.tz_standardize(tz)
        elif tz is not None:
            raise pytz.UnknownTimeZoneError(tz)
        elif tz is None:
            raise TypeError("A 'tz' is required.")

        self._unit = unit
        self._tz = tz

def variable(value, dtype=_FLOATX, name=None):
    '''Instantiates a tensor.

    # Arguments
        value: numpy array, initial value of the tensor.
        dtype: tensor type.
        name: optional name string for the tensor.

    # Returns
        Tensor variable instance.
    '''
    v = tf.Variable(value, dtype=_convert_string_dtype(dtype), name=name)
    if _MANUAL_VAR_INIT:
        return v
    if tf.get_default_graph() is get_session().graph:
        try:
            get_session().run(v.initializer)
        except tf.errors.InvalidArgumentError:
            warnings.warn('Could not automatically initialize variable, '
                          'make sure you do it manually (e.g. via '
                          '`tf.initialize_all_variables()`).')
    else:
        warnings.warn('The default TensorFlow graph is not the graph '
                      'associated with the TensorFlow session currently '
                      'registered with Keras, and as such Keras '
                      'was not able to automatically initialize a variable. '
                      'You should consider registering the proper session '
                      'with Keras via `K.set_session(sess)`.')
    return v

    def load(self, path=None, force=True):
        """Load state from local file.
        If no path is specified, attempts to load from ``self.path``.

        :type path: str
        :arg path: local file to load from

        :type force: bool
        :param force:
            if ``force=False``, only load from ``self.path`` if file
            has changed since last load.

            .. deprecated:: 1.6
                This keyword will be removed in Passlib 1.8;
                Applications should use :meth:`load_if_changed` instead.
        """
        if path is not None:
            with open(path, "rb") as fh:
                self._mtime = 0
                self._load_lines(fh)
        elif not force:
            warn("%(name)s.load(force=False) is deprecated as of Passlib 1.6,"
                 "and will be removed in Passlib 1.8; "
                 "use %(name)s.load_if_changed() instead." %
                 dict(name=self.__class__.__name__),
                 DeprecationWarning, stacklevel=2)
            return self.load_if_changed()
        elif self._path:
            with open(self._path, "rb") as fh:
                self._mtime = os.path.getmtime(self._path)
                self._load_lines(fh)
        else:
            raise RuntimeError("%s().path is not set, an explicit path is required" %
                               self.__class__.__name__)
        return True

    def __init__(self, path=None, new=False, autoload=True, autosave=False,
                 encoding="utf-8", return_unicode=PY3,
                 ):
        # set encoding
        if not encoding:
            warn("``encoding=None`` is deprecated as of Passlib 1.6, "
                 "and will cause a ValueError in Passlib 1.8, "
                 "use ``return_unicode=False`` instead.",
                 DeprecationWarning, stacklevel=2)
            encoding = "utf-8"
            return_unicode = False
        elif not is_ascii_codec(encoding):
            # htpasswd/htdigest files assumes 1-byte chars, and use ":" separator,
            # so only ascii-compatible encodings are allowed.
            raise ValueError("encoding must be 7-bit ascii compatible")
        self.encoding = encoding

        # set other attrs
        self.return_unicode = return_unicode
        self.autosave = autosave
        self._path = path
        self._mtime = 0

        # init db
        if not autoload:
            warn("``autoload=False`` is deprecated as of Passlib 1.6, "
                 "and will be removed in Passlib 1.8, use ``new=True`` instead",
                 DeprecationWarning, stacklevel=2)
            new = True
        if path and not new:
            self.load()
        else:
            self._records = OrderedDict()

def form_for_instance(instance, form=BaseForm, fields=None,
                      formfield_callback=lambda f, **kwargs: f.formfield(**kwargs)):
    """
    Returns a Form class for the given Django model instance.

    Provide ``form`` if you want to use a custom BaseForm subclass.

    Provide ``formfield_callback`` if you want to define different logic for
    determining the formfield for a given database field. It's a callable that
    takes a database Field instance, plus **kwargs, and returns a form Field
    instance with the given kwargs (i.e. 'initial').
    """
    warn("form_for_instance is deprecated. Use ModelForm instead.",
        PendingDeprecationWarning, stacklevel=3)
    model = instance.__class__
    opts = model._meta
    field_list = []
    for f in opts.fields + opts.many_to_many:
        if not f.editable:
            continue
        if fields and not f.name in fields:
            continue
        current_value = f.value_from_object(instance)
        formfield = formfield_callback(f, initial=current_value)
        if formfield:
            field_list.append((f.name, formfield))
    base_fields = SortedDict(field_list)
    return type(opts.object_name + 'InstanceForm', (form,),
        {'base_fields': base_fields, '_model': model,
         'save': make_instance_save(instance, fields, 'changed')})

def form_for_model(model, form=BaseForm, fields=None,
                   formfield_callback=lambda f: f.formfield()):
    """
    Returns a Form class for the given Django model class.

    Provide ``form`` if you want to use a custom BaseForm subclass.

    Provide ``formfield_callback`` if you want to define different logic for
    determining the formfield for a given database field. It's a callable that
    takes a database Field instance and returns a form Field instance.
    """
    warn("form_for_model is deprecated. Use ModelForm instead.",
        PendingDeprecationWarning, stacklevel=3)
    opts = model._meta
    field_list = []
    for f in opts.fields + opts.many_to_many:
        if not f.editable:
            continue
        if fields and not f.name in fields:
            continue
        formfield = formfield_callback(f)
        if formfield:
            field_list.append((f.name, formfield))
    base_fields = SortedDict(field_list)
    return type(opts.object_name + 'Form', (form,),
        {'base_fields': base_fields, '_model': model,
         'save': make_model_save(model, fields, 'created')})

    def load(cls, dirname=''):
        normdir = os.path.normpath(dirname)
        code, data = _run_command(['svn', 'info', normdir])
        # Must check for some contents, as some use empty directories
        # in testcases
        svn_dir = os.path.join(normdir, '.svn')
        has_svn = (os.path.isfile(os.path.join(svn_dir, 'entries')) or
                   os.path.isfile(os.path.join(svn_dir, 'dir-props')) or
                   os.path.isfile(os.path.join(svn_dir, 'dir-prop-base')))

        svn_version = tuple(cls.get_svn_version().split('.'))

        try:
            base_svn_version = tuple(int(x) for x in svn_version[:2])
        except ValueError:
            base_svn_version = tuple()

        if has_svn and (code or not base_svn_version 
                             or base_svn_version < (1, 3)):
            warnings.warn(("No SVN 1.3+ command found: falling back "
                           "on pre 1.7 .svn parsing"), DeprecationWarning)
            return SvnFileInfo(dirname)
        elif not has_svn:
            return SvnInfo(dirname)
        elif base_svn_version < (1, 5):
            return Svn13Info(dirname)
        else:
            return Svn15Info(dirname)

    def __call__(self, method_name, **method_kwargs):
        response = self.method_request(method_name, **method_kwargs)
        response.raise_for_status()

        # there are may be 2 dicts in 1 json
        # for example: {'error': ...}{'response': ...}
        errors = []
        error_codes = []
        for data in json_iter_parse(response.text):
            if 'error' in data:
                error_data = data['error']
                if error_data['error_code'] == CAPTCHA_IS_NEEDED:
                    return self.captcha_is_needed(error_data, method_name, **method_kwargs)

                error_codes.append(error_data['error_code'])
                errors.append(error_data)

            if 'response' in data:
                for error in errors:
                    warnings.warn(str(error))

                # return make_handy(data['response'])
                return data['response']
            
        if INTERNAL_SERVER_ERROR in error_codes:  # invalid access token
            self.get_access_token()
            return self(method_name, **method_kwargs)
        else:
            raise VkAPIMethodError(errors[0])

    def _get_json(self, urlpath):
        """Retrieve a JSON from the HiSPARC API

        :param urlpath: api urlpath to retrieve (i.e. after API_BASE).
        :return: the data returned by the api as dictionary or integer.

        """
        if self.force_fresh and self.force_stale:
            raise Exception('Can not force fresh and stale simultaneously.')
        try:
            if self.force_stale:
                raise Exception
            json_data = self._retrieve_url(urlpath)
            data = json.loads(json_data)
        except Exception:
            if self.force_fresh:
                raise Exception('Couldn\'t get requested data from server.')
            localpath = path.join(LOCAL_BASE,
                                  urlpath.strip('/') + extsep + 'json')
            try:
                with open(localpath) as localdata:
                    data = json.load(localdata)
            except:
                if self.force_stale:
                    raise Exception('Couldn\'t find requested data locally.')
                raise Exception('Couldn\'t get requested data from server '
                                'nor find it locally.')
            if not self.force_stale:
                warnings.warn('Using local data. Possibly outdated.')

        return data

    def __init__(self, app_id=None, user_login=None, user_password=None, access_token=None, user_email=None,
                 scope='offline', timeout=1, api_version='5.20'):

        user_login = user_login or user_email

        if (not user_login or not user_password) and not access_token:
            raise ValueError('Arguments user_login and user_password, or access_token are required')

        if user_email:  # deprecated at April 11, 2014
            warnings.simplefilter('once')
            warnings.warn("Use 'user_login' instead of deprecated 'user_email'", DeprecationWarning, stacklevel=2)

        self.app_id = app_id

        self.user_login = user_login
        self.user_password = user_password

        self.access_token = access_token
        self.scope = scope or ''
        
        self.api_version = api_version

        self._default_timeout = timeout

        self.session = requests.Session()
        self.session.headers['Accept'] = 'application/json'
        self.session.headers['Content-Type'] = 'application/x-www-form-urlencoded'

        if not access_token and user_login and user_password:
            self.get_access_token()