def METHOD_NAME(ftp_writable):
    host, port, user, pw = ftp_writable
    fo = fsspec.open("ftp://{}:{}@{}:{}/out".format(user, pw, host, port), "wb")
    with fo as f:
        f.write(b"hello")
    fo = fsspec.open("ftp://{}:{}@{}:{}/out".format(user, pw, host, port), "rb")
    with fo as f:
        assert f.read() == b"hello"