def METHOD_NAME(
    project_config: ProjectConfig,
) -> SourceTree:
    map_file_to_source = {}
    found_source_files: List[SourceFile] = []
    # TODO: Unify this on the FileTree class level.
    # Introduce #mount_directory method?
    doctree_root_abs_path = os.getcwd()
    doctree_root_abs_path = (
        os.path.dirname(doctree_root_abs_path)
        if os.path.isfile(doctree_root_abs_path)
        else doctree_root_abs_path
    )
    assert isinstance(project_config.export_output_dir, str)
    file_tree = FileFinder.find_files_with_extensions(
        root_path=doctree_root_abs_path,
        ignored_dirs=[project_config.export_output_dir],
        extensions=SourceFileType.all(),
        include_paths=project_config.include_source_paths,
        exclude_paths=project_config.exclude_source_paths,
    )
    root_level = doctree_root_abs_path.count(os.sep)
    file: File
    for _, file, _ in file_tree.iterate():
        in_doctree_source_file_rel_path = os.path.relpath(
            file.root_path, doctree_root_abs_path
        )
        last_folder_in_path: str = os.path.relpath(
            file.get_folder_path(), doctree_root_abs_path
        )
        output_dir_full_path: str = os.path.join(
            project_config.export_output_html_root,
            "_source_files",
            last_folder_in_path,
        )
        Path(output_dir_full_path).mkdir(parents=True, exist_ok=True)
        output_file_name = f"{file.get_file_name()}.html"
        output_file_full_path = os.path.join(
            output_dir_full_path, output_file_name
        )
        level = file.get_folder_path().count(os.sep) - root_level
        source_file = SourceFile(
            level,
            file.root_path,
            in_doctree_source_file_rel_path,
            output_dir_full_path,
            output_file_full_path,
        )
        found_source_files.append(source_file)
        map_file_to_source[file] = source_file
    source_tree = SourceTree(
        file_tree, found_source_files, map_file_to_source
    )
    return source_tree