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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def remove(ctx, client, sources):
 """Remove files and check repository for potential problems."""

    from renku.api._git import _expand_directories

    def fmt_path(path):
        """Format path as relative to the client path."""
        return str(Path(path).absolute().relative_to(client.path))

    files = {
        fmt_path(source): fmt_path(file_or_dir)
        for file_or_dir in sources
        for source in _expand_directories((file_or_dir, ))
    }

    # 1. Update dataset metadata files.
    with progressbar(
        client.datasets.values(),
        item_show_func=lambda item: str(item.short_id) if item else '',
        label='Updating dataset metadata',
        width=0,
    ) as bar:
        for dataset in bar:
            remove = []
            for key, file_ in dataset.files.items():
                filepath = fmt_path(file_.full_path)
                if filepath in files:
                    remove.append(key)

            if remove:
                for key in remove:
                    dataset.unlink_file(key)

                dataset.to_yaml()

    # 2. Manage .gitattributes for external storage.
    tracked = tuple(
        path for path, attr in client.find_attr(*files).items()
        if attr.get('filter') == 'lfs'
    )
    client.untrack_paths_from_storage(*tracked)
    existing = client.find_attr(*tracked)
    if existing:
        click.echo(WARNING + 'There are custom .gitattributes.\n')
        if click.confirm(
            'Do you want to edit ".gitattributes" now?', default=False
        ):
            click.edit(filename=str(client.path / '.gitattributes'))

    # Finally remove the files.
    final_sources = list(set(files.values()))
    if final_sources:
        run(['git', 'rm', '-rf'] + final_sources, check=True)