How to use the unidiff.patch.PatchedFile function in unidiff

def setUp(self):
        super(TestPatchedFile, self).setUp()
        self.patched_file = PatchedFile()

def __init__(self, patch_info=None, source='', target='',
                 source_timestamp=None, target_timestamp=None,
                 is_binary_file=False, is_rename=False):
        super(PatchedFile, self).__init__()
        self.patch_info = patch_info
        self.source_file = source
        self.source_timestamp = source_timestamp
        self.target_file = target
        self.target_timestamp = target_timestamp
        self.is_binary_file = is_binary_file
        self.is_rename = is_rename

# (in that case, source files should match)
                if current_file is not None and not (current_file.is_rename and
                        current_file.source_file == source_file):
                    current_file = None
                continue

            # check for target file header
            is_target_filename = RE_TARGET_FILENAME.match(line)
            if is_target_filename:
                if current_file is not None and not current_file.is_rename:
                    raise UnidiffParseError('Target without source: %s' % line)
                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)

# reset current file
                current_file = None
                continue

            # check for a git rename, target file
            is_rename_target_filename = RE_RENAME_TARGET_FILENAME.match(line)
            if is_rename_target_filename:
                if current_file is not None:
                    raise UnidiffParseError('Target without source: %s' % line)
                # prefix with 'b/' to match expected git source format
                target_file = (
                    'b/' + is_rename_target_filename.group('filename'))
                # keep line as patch_info
                patch_info.append(line)
                # add current file to PatchSet
                current_file = PatchedFile(
                    patch_info, source_file, target_file, None, None,
                    is_rename=True)
                self.append(current_file)
                continue

            # check for source file header
            is_source_filename = RE_SOURCE_FILENAME.match(line)
            if is_source_filename:
                source_file = is_source_filename.group('filename')
                source_timestamp = is_source_filename.group('timestamp')
                # reset current file, unless we are processing a rename
                # (in that case, source files should match)
                if current_file is not None and not (current_file.is_rename and
                        current_file.source_file == source_file):
                    current_file = None
                continue

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

            is_binary_diff = RE_BINARY_DIFF.match(line)
            if is_binary_diff:
                source_file = is_binary_diff.group('source_filename')
                target_file = is_binary_diff.group('target_filename')
                patch_info.append(line)
                current_file = PatchedFile(
                    patch_info, source_file, target_file, is_binary_file=True)
                self.append(current_file)
                patch_info = None
                current_file = None
                continue

            # if nothing has matched above then this line is a patch info
            if patch_info is None:
                current_file = None
                patch_info = PatchInfo()
            patch_info.append(line)

for line in diff:
        # check for source file header
        check_source = RE_SOURCE_FILENAME.match(line)
        if check_source:
            source_file = check_source.group('filename')
            source_timestamp = check_source.group('timestamp')
            current_patch = None
            continue

        # check for target file header
        check_target = RE_TARGET_FILENAME.match(line)
        if check_target:
            target_file = check_target.group('filename')
            target_timestamp = check_target.group('timestamp')
            current_patch = PatchedFile(source_file, target_file,
                                        source_timestamp, target_timestamp)
            ret.append(current_patch)
            continue

        # check for hunk header
        re_hunk_header = RE_HUNK_HEADER.match(line)
        if re_hunk_header:
            hunk_info = re_hunk_header.groups()
            hunk = _parse_hunk(diff, *hunk_info)
            current_patch.append(hunk)
    return ret