How to use the unidiff.errors.UnidiffParseError function in unidiff

def _parse_hunk(diff, source_start, source_len, target_start, target_len,
                section_header):
    """Parse a diff hunk details."""
    hunk = Hunk(source_start, source_len, target_start, target_len,
                section_header)
    source_line_no = hunk.source_start
    target_line_no = hunk.target_start

    for line in diff:
        valid_line = RE_HUNK_BODY_LINE.match(line)
        if not valid_line:
            raise UnidiffParseError('Hunk diff line expected: %s' % line)

        line_type = valid_line.group('line_type')
        value = valid_line.group('value')
        original_line = Line(value, line_type=line_type)
        if line_type == LINE_TYPE_ADDED:
            original_line.target_line_no = target_line_no
            target_line_no += 1
        elif line_type == LINE_TYPE_REMOVED:
            original_line.source_line_no = source_line_no
            source_line_no += 1
        elif line_type == LINE_TYPE_CONTEXT:
            original_line.target_line_no = target_line_no
            target_line_no += 1
            original_line.source_line_no = source_line_no
            source_line_no += 1
        else:

def _add_no_newline_marker_to_last_hunk(self):
        if not self:
            raise UnidiffParseError(
                'Unexpected marker:' + LINE_VALUE_NO_NEWLINE)
        last_hunk = self[-1]
        last_hunk.append(
            Line(LINE_VALUE_NO_NEWLINE + '\n', line_type=LINE_TYPE_NO_NEWLINE))

target_file = is_target_filename.group('filename')
                target_timestamp = is_target_filename.group('timestamp')
                if current_file is None:
                    # add current file to PatchSet
                    current_file = PatchedFile(
                        patch_info, source_file, target_file,
                        source_timestamp, target_timestamp)
                    self.append(current_file)
                    patch_info = None
                continue

            # check for hunk header
            is_hunk_header = RE_HUNK_HEADER.match(line)
            if is_hunk_header:
                if current_file is None:
                    raise UnidiffParseError('Unexpected hunk found: %s' % line)
                current_file._parse_hunk(line, diff, encoding)
                continue

            # check for no newline marker
            is_no_newline = RE_NO_NEWLINE_MARKER.match(line)
            if is_no_newline:
                if current_file is None:
                    raise UnidiffParseError('Unexpected marker: %s' % line)
                current_file._add_no_newline_marker_to_last_hunk()
                continue

            # sometimes hunks can be followed by empty lines
            if line == '\n' and current_file is not None:
                current_file._append_trailing_empty_line()
                continue

target_line_no > expected_target_end):
                raise UnidiffParseError('Hunk is longer than expected')

            if original_line:
                original_line.diff_line_no = diff_line_no
                hunk.append(original_line)

            # if hunk source/target lengths are ok, hunk is complete
            if (source_line_no == expected_source_end and
                    target_line_no == expected_target_end):
                break

        # report an error if we haven't got expected number of lines
        if (source_line_no < expected_source_end or
                target_line_no < expected_target_end):
            raise UnidiffParseError('Hunk is shorter than expected')

        self.append(hunk)

original_line.source_line_no = source_line_no
                source_line_no += 1
            elif line_type == LINE_TYPE_CONTEXT:
                original_line.target_line_no = target_line_no
                target_line_no += 1
                original_line.source_line_no = source_line_no
                source_line_no += 1
            elif line_type == LINE_TYPE_NO_NEWLINE:
                pass
            else:
                original_line = None

            # stop parsing if we got past expected number of lines
            if (source_line_no > expected_source_end or
                    target_line_no > expected_target_end):
                raise UnidiffParseError('Hunk is longer than expected')

            if original_line:
                original_line.diff_line_no = diff_line_no
                hunk.append(original_line)

            # if hunk source/target lengths are ok, hunk is complete
            if (source_line_no == expected_source_end and
                    target_line_no == expected_target_end):
                break

        # report an error if we haven't got expected number of lines
        if (source_line_no < expected_source_end or
                target_line_no < expected_target_end):
            raise UnidiffParseError('Hunk is shorter than expected')

        self.append(hunk)

source_line_no = hunk.source_start
        target_line_no = hunk.target_start
        expected_source_end = source_line_no + hunk.source_length
        expected_target_end = target_line_no + hunk.target_length

        for diff_line_no, line in diff:
            if encoding is not None:
                line = line.decode(encoding)

            valid_line = RE_HUNK_BODY_LINE.match(line)
            if not valid_line:
                valid_line = RE_HUNK_EMPTY_BODY_LINE.match(line)

            if not valid_line:
                raise UnidiffParseError('Hunk diff line expected: %s' % line)

            line_type = valid_line.group('line_type')
            if line_type == LINE_TYPE_EMPTY:
                line_type = LINE_TYPE_CONTEXT
            value = valid_line.group('value')
            original_line = Line(value, line_type=line_type)
            if line_type == LINE_TYPE_ADDED:
                original_line.target_line_no = target_line_no
                target_line_no += 1
            elif line_type == LINE_TYPE_REMOVED:
                original_line.source_line_no = source_line_no
                source_line_no += 1
            elif line_type == LINE_TYPE_CONTEXT:
                original_line.target_line_no = target_line_no
                target_line_no += 1
                original_line.source_line_no = source_line_no

def _append_trailing_empty_line(self):
        if not self:
            raise UnidiffParseError('Unexpected trailing newline character')
        last_hunk = self[-1]
        last_hunk.append(Line('\n', line_type=LINE_TYPE_EMPTY))

def load_from_diff(self, diff, exclude_regex='', baseline_file='', last_commit_hash='', repo_name=''):
        """Initializes a SecretsCollection object from diff.
        Not a classmethod, since it needs the list of self.plugins for secret scanning.

        :param diff: string; diff string
        :param exclude_regex: string; a regular expression of what files to skip over
        :param baseline_file: string or None; the baseline_file of the repo, to skip over since it contains hashes
        :param last_commit_hash: string; used for logging only -- the last hash we saved
        :param repo_name: string; used for logging only -- the name of the repo
        """
        try:
            patch_set = PatchSet.from_string(diff)
        except UnidiffParseError:  # pragma: no cover
            alert = {
                'alert': 'UnidiffParseError',
                'hash': last_commit_hash,
                'repo_name': repo_name,
            }
            CustomLogObj.getLogger().error(alert)
            raise

        if exclude_regex:
            regex = re.compile(exclude_regex, re.IGNORECASE)

        for patch_file in patch_set:
            filename = patch_file.path
            # If the file matches the exclude_regex, we skip it
            if exclude_regex and regex.search(filename):
                continue