functions.py

def file_to_load() -> Parallelizable[str]:
    for file_ in _list_files(...):
        yield file_


def file_contents(file_to_load: str) -> str:
    with open(file_to_load) as f:
        return f.read()


def all_contents(file_contents: Collect[str]) -> str:
    out = "".join(file_contents)
    return out