How to use the pyyaml.serializer.SerializerError function in PyYAML

def open(self):
        if self.closed is None:
            self.emit(StreamStartEvent(encoding=self.use_encoding))
            self.closed = False
        elif self.closed:
            raise SerializerError("serializer is closed")
        else:
            raise SerializerError("serializer is already opened")

def close(self):
        if self.closed is None:
            raise SerializerError("serializer is not opened")
        elif not self.closed:
            self.emit(StreamEndEvent())
            self.closed = True

def serialize(self, node):
        if self.closed is None:
            raise SerializerError("serializer is not opened")
        elif self.closed:
            raise SerializerError("serializer is closed")
        self.emit(DocumentStartEvent(explicit=self.use_explicit_start,
            version=self.use_version, tags=self.use_tags))
        self.anchor_node(node)
        self.serialize_node(node, None, None)
        self.emit(DocumentEndEvent(explicit=self.use_explicit_end))
        self.serialized_nodes = {}
        self.anchors = {}
        self.last_anchor_id = 0

def open(self):
        if self.closed is None:
            self.emit(StreamStartEvent(encoding=self.use_encoding))
            self.closed = False
        elif self.closed:
            raise SerializerError("serializer is closed")
        else:
            raise SerializerError("serializer is already opened")

def serialize(self, node):
        if self.closed is None:
            raise SerializerError("serializer is not opened")
        elif self.closed:
            raise SerializerError("serializer is closed")
        self.emit(DocumentStartEvent(explicit=self.use_explicit_start,
            version=self.use_version, tags=self.use_tags))
        self.anchor_node(node)
        self.serialize_node(node, None, None)
        self.emit(DocumentEndEvent(explicit=self.use_explicit_end))
        self.serialized_nodes = {}
        self.anchors = {}
        self.last_anchor_id = 0