How to use the soco.didl_lite.Container function in soco

def add_item(self, item):
        if isinstance(item, Item):
            Container.add_item(self, item)
            return True
        return False

def to_didl_element(self):
        """ Returns an Element based on this Resource.
        """
        root = Container.to_didl_element(self)

        if not all([self.storage_total, self.storage_used, self.storage_free,
                    self.storage_medium]):
            raise Exception('Could not create DIDL Element: missing required '
                            'properties.')

        ElementTree.SubElement(root, 'upnp:storageTotal').text = \
            self.storage_total
        ElementTree.SubElement(root, 'upnp:storageUsed').text = \
            self.storage_used
        ElementTree.SubElement(root, 'upnp:storageFree').text = \
            self.storage_free
        ElementTree.SubElement(root, 'upnp:storageMedium').text = \
            self.storage_medium

        return root

ElementTree.SubElement(root, 'upnp:author').text = a
        for p in self.publishers:
            ElementTree.SubElement(root, 'dc:publisher').text = p
        for c in self.contributors:
            ElementTree.SubElement(root, 'dc:contributor').text = c
        for r in self.relations:
            ElementTree.SubElement(root, 'dc:relation').text = r
        for l in self.languages:
            ElementTree.SubElement(root, 'dc:language').text = l
        for r in self.rights:
            ElementTree.SubElement(root, 'dc:rights').text = r

        return root


class Album(Container):

    """ Ordered collection of objects. Rendering the album has the semantics of
    rendering each object in sequence.
    """
    upnp_class = '%s%s' % (Container.upnp_class, '.album')

    def __init__(self, object_id='', parent_id='', title='', restricted=False,
                 creator='', write_status=WRITE_STATUS_NOT_WRITABLE,
                 searchable=True, search_classes=None, create_classes=None,
                 storage_medium='', long_description='', description='',
                 publishers=None, contributors=None, date='', relations=None,
                 rights=None):
        """ Constructor for the Album class.

        @param id: unique identifier for the object
        @param parent_id: id of object's parent

for a in self.artists:
            ElementTree.SubElement(root, 'upnp:artist').text = a
        for g in self.genres:
            ElementTree.SubElement(root, 'upnp:genre').text = g
        for p in self.producers:
            ElementTree.SubElement(root, 'upnp:producer').text = p
        if self.album_art_uri:
            ElementTree.SubElement(root, 'upnp:albumArtURI').text = \
                self.album_art_uri
        if self.toc:
            ElementTree.SubElement(root, 'upnp:toc').text = self.toc

        return root


class Genre(Container):

    """ A container with a name denoting a genre.
    """
    upnp_class = '%s%s' % (Container.upnp_class, '.genre')

    def __init__(self, object_id='', parent_id='', title='', restricted=False,
                 creator='', write_status=WRITE_STATUS_NOT_WRITABLE,
                 searchable=True, search_classes=None, create_classes=None,
                 long_description='', description=''):
        """ Constructor for the Container class.

        @param id: unique identifier for the object
        @param parent_id: id of object's parent
        @param title: name of the object
        @param restricted: True if only CDS can modify the object
        @param creator: content creator or owner

def add_container(self, c):
        if isinstance(c, Album) or isinstance(c, PlaylistContainer):
            Container.add_container(self, c)
            return True
        return False

for r in self.relations:
            ElementTree.SubElement(root, 'dc:relation').text = r
        for l in self.languages:
            ElementTree.SubElement(root, 'dc:language').text = l
        for r in self.rights:
            ElementTree.SubElement(root, 'dc:rights').text = r

        return root


class Album(Container):

    """ Ordered collection of objects. Rendering the album has the semantics of
    rendering each object in sequence.
    """
    upnp_class = '%s%s' % (Container.upnp_class, '.album')

    def __init__(self, object_id='', parent_id='', title='', restricted=False,
                 creator='', write_status=WRITE_STATUS_NOT_WRITABLE,
                 searchable=True, search_classes=None, create_classes=None,
                 storage_medium='', long_description='', description='',
                 publishers=None, contributors=None, date='', relations=None,
                 rights=None):
        """ Constructor for the Album class.

        @param id: unique identifier for the object
        @param parent_id: id of object's parent
        @param title: name of the object
        @param restricted: True if only CDS can modify the object
        @param creator: content creator or owner
        @param write_status: modifiability of the resources of this object.
                             Integer parameter based on WRITE_STATUS_*

def to_didl_element(self):
        """ Returns an Element based on this Resource.
        """
        root = Person.to_didl_element(self)

        for g in self.genres:
            ElementTree.SubElement(root, 'upnp:genre').text = g

        if self.artist_discography_uri:
            ElementTree.SubElement(root, 'upnp:artistDiscographyURI').text = \
                self.artist_discography_uri

        return root


class StorageSystem(Container):

    """ Heterogeneous collection of storage media. May only be child of the
    root container or another StorageSystem container.
    """
    upnp_class = '%s%s' % (Container.upnp_class, '.storageSystem')

    def __init__(self, object_id='', parent_id='', title='', restricted=False,
                 creator='', write_status=WRITE_STATUS_NOT_WRITABLE,
                 searchable=True, search_classes=None, create_classes=None,
                 storage_total=0, storage_used=0, storage_free=0,
                 storage_max_partition=0, storage_medium=''):
        """ Constructor for the StorageSystem class.

        @param id: unique identifier for the object
        @param parent_id: id of object's parent
        @param title: name of the object

if self.long_description:
            ElementTree.SubElement(root, 'upnp:longDescription').text = \
                self.long_description
        if self.storage_medium:
            ElementTree.SubElement(root, 'upnp:storageMedium').text = \
                self.storage_medium
        if self.description:
            ElementTree.SubElement(root, 'dc:description').text = \
                self.description
        if self.date:
            ElementTree.SubElement(root, 'dc:date').text = self.date

        return root


class Person(Container):

    """ Unordered collection of objects that belong to a person.
    """
    upnp_class = '%s%s' % (Container.upnp_class, '.person')

    def __init__(self, object_id='', parent_id='', title='', restricted=False,
                 creator='', write_status=WRITE_STATUS_NOT_WRITABLE,
                 searchable=True, search_classes=None, create_classes=None,
                 languages=None):
        """ Constructor for the Person class.

        @param id: unique identifier for the object
        @param parent_id: id of object's parent
        @param title: name of the object
        @param restricted: True if only CDS can modify the object
        @param creator: content creator or owner

ElementTree.SubElement(root, 'upnp:storageTotal').text = \
            self.storage_total
        ElementTree.SubElement(root, 'upnp:storageUsed').text = \
            self.storage_used
        ElementTree.SubElement(root, 'upnp:storageFree').text = \
            self.storage_free
        ElementTree.SubElement(root, 'upnp:storageMaxPartition').text = \
            self.storage_max_partition
        ElementTree.SubElement(root, 'upnp:storageMedium').text = \
            self.storage_medium

        return root


class StorageVolume(Container):

    """ Some physical storage unit of a single type. May only be a child of the
    root container or a StorageSystem container.
    """
    upnp_class = '%s%s' % (Container.upnp_class, '.storageVolume')

    def __init__(
            self, object_id='', parent_id='', title='', restricted=False,
            creator='', write_status=WRITE_STATUS_NOT_WRITABLE,
            searchable=True, search_classes=None, create_classes=None,
            storage_total=0, storage_used=0, storage_free=0,
            storage_medium=''):
        """ Constructor for the StorageVolume class.

        @param id: unique identifier for the object
        @param parent_id: id of object's parent

raise Exception('Could not create DIDL Element: missing required '
                            'properties.')

        ElementTree.SubElement(root, 'upnp:storageTotal').text = \
            self.storage_total
        ElementTree.SubElement(root, 'upnp:storageUsed').text = \
            self.storage_used
        ElementTree.SubElement(root, 'upnp:storageFree').text = \
            self.storage_free
        ElementTree.SubElement(root, 'upnp:storageMedium').text = \
            self.storage_medium

        return root


class StorageFolder(Container):

    """ Collection of objects stored on some storage medium. May only be a
    child of the root container or another storage container.
    """
    upnp_class = '%s%s' % (Container.upnp_class, '.storageFolder')

    def __init__(self, object_id='', parent_id='', title='', restricted=False,
                 creator='', write_status=WRITE_STATUS_NOT_WRITABLE,
                 searchable=True, search_classes=None, create_classes=None,
                 storage_used=''):
        """ Constructor for the StorageFolder class.

        @param id: unique identifier for the object
        @param parent_id: id of object's parent
        @param title: name of the object
        @param restricted: True if only CDS can modify the object