def METHOD_NAME(ftp_writable):
    # not the same as test_read_block in test_utils, this depends on the
    # behaviour of the bytest caching
    from fsspec.utils import read_block
    host, port, user, pw = ftp_writable
    fs = FTPFileSystem(host=host, port=port, username=user, password=pw)
    fn = "/myfile"
    with fs.open(fn, "wb") as f:
        f.write(b"a,b\n1,2")
    f = fs.open(fn, "rb", cache_type="bytes")
    assert read_block(f, 0, 6400, b"\n") == b"a,b\n1,2"