def update(self, modifier, dest_dir=None, **kwargs):
        """
        Update the contents of a wheel in a generic way. The modifier should
        be a callable which expects a dictionary argument: its keys are
        archive-entry paths, and its values are absolute filesystem paths
        where the contents the corresponding archive entries can be found. The
        modifier is free to change the contents of the files pointed to, add
        new entries and remove entries, before returning. This method will
        extract the entire contents of the wheel to a temporary location, call
        the modifier, and then use the passed (and possibly updated)
        dictionary to write a new wheel. If ``dest_dir`` is specified, the new
        wheel is written there -- otherwise, the original wheel is overwritten.

        The modifier should return True if it updated the wheel, else False.
        This method returns the same value the modifier returns.
        """

        def get_version(path_map, info_dir):
            version = path = None
            key = '%s/%s' % (info_dir, METADATA_FILENAME)
            if key not in path_map:
                key = '%s/PKG-INFO' % info_dir
            if key in path_map:
                path = path_map[key]
                version = Metadata(path=path).version
            return version, path

        def update_version(version, path):
            updated = None
            try:
                v = NormalizedVersion(version)
                i = version.find('-')
                if i < 0:
                    updated = '%s+1' % version
                else:
                    parts = [int(s) for s in version[i + 1:].split('.')]
                    parts[-1] += 1
                    updated = '%s+%s' % (version[:i],
                                         '.'.join(str(i) for i in parts))
            except UnsupportedVersionError:
                logger.debug('Cannot update non-compliant (PEP-440) '
                             'version %r', version)
            if updated:
                md = Metadata(path=path)
                md.version = updated
                legacy = not path.endswith(METADATA_FILENAME)
                md.write(path=path, legacy=legacy)
                logger.debug('Version updated from %r to %r', version,
                             updated)

        pathname = os.path.join(self.dirname, self.filename)
        name_ver = '%s-%s' % (self.name, self.version)
        info_dir = '%s.dist-info' % name_ver
        record_name = posixpath.join(info_dir, 'RECORD')
        with tempdir() as workdir:
            with ZipFile(pathname, 'r') as zf:
                path_map = {}
                for zinfo in zf.infolist():
                    arcname = zinfo.filename
                    if isinstance(arcname, text_type):
                        u_arcname = arcname
                    else:
                        u_arcname = arcname.decode('utf-8')
                    if u_arcname == record_name:
                        continue
                    if '..' in u_arcname:
                        raise DistlibException('invalid entry in '
                                               'wheel: %r' % u_arcname)
                    zf.extract(zinfo, workdir)
                    path = os.path.join(workdir, convert_path(u_arcname))
                    path_map[u_arcname] = path

            # Remember the version.
            original_version, _ = get_version(path_map, info_dir)
            # Files extracted. Call the modifier.
            modified = modifier(path_map, **kwargs)
            if modified:
                # Something changed - need to build a new wheel.
                current_version, path = get_version(path_map, info_dir)
                if current_version and (current_version == original_version):
                    # Add or update local version to signify changes.
                    update_version(current_version, path)
                # Decide where the new wheel goes.
                if dest_dir is None:
                    fd, newpath = tempfile.mkstemp(suffix='.whl',
                                                   prefix='wheel-update-',
                                                   dir=workdir)
                    os.close(fd)
                else:
                    if not os.path.isdir(dest_dir):
                        raise DistlibException('Not a directory: %r' % dest_dir)
                    newpath = os.path.join(dest_dir, self.filename)
                archive_paths = list(path_map.items())
                distinfo = os.path.join(workdir, info_dir)
                info = distinfo, info_dir
                self.write_records(info, workdir, archive_paths)
                self.build_zip(newpath, archive_paths)
                if dest_dir is None:
                    shutil.copyfile(newpath, pathname)
        return modified
Update the contents of a wheel in a generic way. The modifier should
        be a callable which expects a dictionary argument: its keys are
        archive-entry paths, and its values are absolute filesystem paths
        where the contents the corresponding archive entries can be found. The
        modifier is free to change the contents of the files pointed to, add
        new entries and remove entries, before returning. This method will
        extract the entire contents of the wheel to a temporary location, call
        the modifier, and then use the passed (and possibly updated)
        dictionary to write a new wheel. If ``dest_dir`` is specified, the new
        wheel is written there -- otherwise, the original wheel is overwritten.

        The modifier should return True if it updated the wheel, else False.
        This method returns the same value the modifier returns.