How to use the circuits.web.parsers.multipart.MultipartError function in circuits

def write_header(self, line, nl):
        line = line.decode(self.charset or 'latin1')
        if not nl: raise MultipartError('Unexpected end of line in header.')
        if not line.strip(): # blank line -> end of header segment
            self.finish_header()
        elif line[0] in ' \t' and self.headerlist:
            name, value = self.headerlist.pop()
            self.headerlist.append((name, value+line.strip()))
        else:
            if ':' not in line:
                raise MultipartError("Syntax error in header: No colon.")
            name, value = line.split(':', 1)
            self.headerlist.append((name.strip(), value.strip()))

def write_header(self, line, nl):
        line = line.decode(self.charset or 'latin1')
        if not nl: raise MultipartError('Unexpected end of line in header.')
        if not line.strip(): # blank line -> end of header segment
            self.finish_header()
        elif line[0] in ' \t' and self.headerlist:
            name, value = self.headerlist.pop()
            self.headerlist.append((name, value+line.strip()))
        else:
            if ':' not in line:
                raise MultipartError("Syntax error in header: No colon.")
            name, value = line.split(':', 1)
            self.headerlist.append((name.strip(), value.strip()))

def write_body(self, line, nl):
        if not line and not nl: return # This does not even flush the buffer
        self.size += len(line) + len(self._buf)
        self.file.write(self._buf + line)
        self._buf = nl
        if self.content_length > 0 and self.size > self.content_length:
            raise MultipartError('Size of body exceeds Content-Length header.')
        if self.size > self.memfile_limit and isinstance(self.file, BytesIO):
            # TODO: What about non-file uploads that exceed the memfile_limit?
            self.file, old = TemporaryFile(mode='w+b'), self.file
            old.seek(0)
            copy_file(old, self.file, self.size, self.buffer_size)

''' Parse a multipart/form-data byte stream. This object is an iterator
            over the parts of the message.

            :param stream: A file-like stream. Must implement ``.read(size)``.
            :param boundary: The multipart boundary as a byte string.
            :param content_length: The maximum number of bytes to read.
        '''
        self.stream, self.boundary = stream, boundary
        self.content_length = content_length
        self.disk_limit = disk_limit
        self.memfile_limit = memfile_limit
        self.mem_limit = min(mem_limit, self.disk_limit)
        self.buffer_size = min(buffer_size, self.mem_limit)
        self.charset = charset
        if self.buffer_size - 6 < len(boundary):  # "--boundary--\r\n"
            raise MultipartError('Boundary does not fit into buffer_size.')
        self._done = []
        self._part_iter = None

mem_used += part.size
                else:
                    disk_used += part.size
                part.file.seek(0)
                yield part
                part = MultipartPart(**opts)
            else:
                is_tail = not nl  # The next line continues this one
                part.feed(line, nl)
                if part.is_buffered():
                    if part.size + mem_used > self.mem_limit:
                        raise MultipartError("Memory limit reached.")
                elif part.size + disk_used > self.disk_limit:
                    raise MultipartError("Disk limit reached.")
        if line != terminator:
            raise MultipartError("Unexpected end of multipart stream.")

(text_type) and lists as values (multiple values per key are possible).
        The forms-dictionary contains form-field values as text_type strings.
        The files-dictionary contains :class:`MultipartPart` instances, either
        because the form-field was a file-upload or the value is to big to fit
        into memory limits.

        :param environ: An WSGI environment dict.
        :param charset: The charset to use if unsure. (default: utf8)
        :param strict: If True, raise :exc:`MultipartError` on any parsing
                       errors. These are silently ignored by default.
    '''

    forms, files = MultiDict(), MultiDict()
    try:
        if environ.get('REQUEST_METHOD', 'GET').upper() not in ('POST', 'PUT'):
            raise MultipartError("Request method other than POST or PUT.")
        content_length = int(environ.get('CONTENT_LENGTH', '-1'))
        content_type = environ.get('CONTENT_TYPE', '')
        if not content_type:
            raise MultipartError("Missing Content-Type header.")
        content_type, options = parse_options_header(content_type)
        stream = environ.get('wsgi.input') or BytesIO()
        kw['charset'] = charset = options.get('charset', charset)
        if content_type == 'multipart/form-data':
            boundary = options.get('boundary', '')
            if not boundary:
                raise MultipartError("No boundary for multipart/form-data.")
            for part in MultipartParser(stream, boundary, content_length, **kw):
                if part.filename or not part.is_buffered():
                    files[part.name] = part
                else:  # TODO: Big form-fields are in the files dict. really?
                    forms[part.name] = part.value

def finish_header(self):
        self.file = BytesIO()
        self.headers = Headers(self.headerlist)
        cdis = self.headers.get('Content-Disposition','')
        ctype = self.headers.get('Content-Type','')
        clen = self.headers.get('Content-Length','-1')
        if not cdis:
            raise MultipartError('Content-Disposition header is missing.')
        self.disposition, self.options = parse_options_header(cdis)
        self.name = self.options.get('name')
        self.filename = self.options.get('filename')
        self.content_type, options = parse_options_header(ctype)
        self.charset = options.get('charset') or self.charset
        self.content_length = int(self.headers.get('Content-Length','-1'))

elif line == separator and not is_tail:
                if part.is_buffered(): mem_used  += part.size
                else:                  disk_used += part.size
                part.file.seek(0)
                yield part
                part = MultipartPart(**opts)
            else:
                is_tail = not nl # The next line continues this one
                part.feed(line, nl)
                if part.is_buffered():
                    if part.size + mem_used > self.mem_limit:
                        raise MultipartError("Memory limit reached.")
                elif part.size + disk_used > self.disk_limit:
                    raise MultipartError("Disk limit reached.")
        if line != terminator:
            raise MultipartError("Unexpected end of multipart stream.")

def finish_header(self):
        self.file = BytesIO()
        self.headers = Headers(self.headerlist)
        cdis = self.headers.get('Content-Disposition', '')
        ctype = self.headers.get('Content-Type', '')
        self.headers.get('Content-Length', '-1')
        if not cdis:
            raise MultipartError('Content-Disposition header is missing.')
        self.disposition, self.options = parse_options_header(cdis)
        self.name = self.options.get('name')
        self.filename = self.options.get('filename')
        self.content_type, options = parse_options_header(ctype)
        self.charset = options.get('charset') or self.charset
        self.content_length = int(self.headers.get('Content-Length', '-1'))

def write_body(self, line, nl):
        if not line and not nl:
            return  # This does not even flush the buffer
        self.size += len(line) + len(self._buf)
        self.file.write(self._buf + line)
        self._buf = nl
        if self.content_length > 0 and self.size > self.content_length:
            raise MultipartError('Size of body exceeds Content-Length header.')
        if self.size > self.memfile_limit and isinstance(self.file, BytesIO):
            # TODO: What about non-file uploads that exceed the memfile_limit?
            self.file, old = TemporaryFile(mode='w+b'), self.file
            old.seek(0)
            copy_file(old, self.file, self.size, self.buffer_size)