How to use the pyyaml.lib.yaml.emitter.EmitterError function in PyYAML

def expect_alias(self):
        if self.event.anchor is None:
            raise EmitterError("anchor is not specified for alias")
        self.process_anchor(u'*')
        self.state = self.states.pop()

def expect_nothing(self):
        raise EmitterError("expected nothing, but got %s" % self.event)

if isinstance(self.event, ScalarEvent):
                self.expect_scalar()
            elif isinstance(self.event, SequenceStartEvent):
                if self.flow_level or self.canonical or self.event.flow_style   \
                        or self.check_empty_sequence():
                    self.expect_flow_sequence()
                else:
                    self.expect_block_sequence()
            elif isinstance(self.event, MappingStartEvent):
                if self.flow_level or self.canonical or self.event.flow_style   \
                        or self.check_empty_mapping():
                    self.expect_flow_mapping()
                else:
                    self.expect_block_mapping()
        else:
            raise EmitterError("expected NodeEvent, but got %s" % self.event)

def prepare_anchor(self, anchor):
        if not anchor:
            raise EmitterError("anchor must not be empty")
        for ch in anchor:
            if not (u'0' <= ch <= u'9' or u'A' <= ch <= 'Z' or u'a' <= ch <= 'z'    \
                    or ch in u'-_'):
                raise EmitterError("invalid character %r in the anchor: %r"
                        % (ch.encode('utf-8'), anchor.encode('utf-8')))
        return anchor

def prepare_tag_handle(self, handle):
        if not handle:
            raise EmitterError("tag handle must not be empty")
        if handle[0] != u'!' or handle[-1] != u'!':
            raise EmitterError("tag handle must start and end with '!': %r"
                    % (handle.encode('utf-8')))
        for ch in handle[1:-1]:
            if not (u'0' <= ch <= u'9' or u'A' <= ch <= 'Z' or u'a' <= ch <= 'z'    \
                    or ch in u'-_'):
                raise EmitterError("invalid character %r in the tag handle: %r"
                        % (ch.encode('utf-8'), handle.encode('utf-8')))
        return handle

def expect_stream_start(self):
        if isinstance(self.event, StreamStartEvent):
            if self.event.encoding:
                self.encoding = self.event.encoding
            self.write_stream_start()
            self.state = self.expect_first_document_start
        else:
            raise EmitterError("expected StreamStartEvent, but got %s"
                    % self.event)

def prepare_tag_prefix(self, prefix):
        if not prefix:
            raise EmitterError("tag prefix must not be empty")
        chunks = []
        start = end = 0
        if prefix[0] == u'!':
            end = 1
        while end < len(prefix):
            ch = prefix[end]
            if u'0' <= ch <= u'9' or u'A' <= ch <= 'Z' or u'a' <= ch <= 'z'  \
                    or ch in u'-;/?!:@&=+$,_.~*\'()[]':
                end += 1
            else:
                if start < end:
                    chunks.append(prefix[start:end])
                start = end = end+1
                data = ch.encode('utf-8')
                for ch in data:
                    chunks.append(u'%%%02X' % ord(ch))

def prepare_anchor(self, anchor):
        if not anchor:
            raise EmitterError("anchor must not be empty")
        for ch in anchor:
            if not (u'0' <= ch <= u'9' or u'A' <= ch <= 'Z' or u'a' <= ch <= 'z'    \
                    or ch in u'-_'):
                raise EmitterError("invalid character %r in the anchor: %r"
                        % (ch.encode('utf-8'), anchor.encode('utf-8')))
        return anchor

def expect_document_end(self):
        if isinstance(self.event, DocumentEndEvent):
            self.write_indent()
            if self.event.explicit:
                self.write_indicator(u'...', True)
                self.write_indent()
            self.flush_stream()
            self.state = self.expect_document_start
        else:
            raise EmitterError("expected DocumentEndEvent, but got %s"
                    % self.event)