strategies.py

        seen = set()
        for n in nodes.flatten():
            si = n.get_storage_index()
            if si in seen:
                return False
            seen.add(si)
        return True

    return recursive(leaf_nodes(), directory_nodes,).filter(
        storage_indexes_are_distinct,
    )


def pass_counts():
    """
    Build integers usable as a number of passes to work on.  There is always
    at least one pass in a group and there are never "too many", whatever that
    means.
    """
    return integers(min_value=1, max_value=2 ** 8)


def api_auth_tokens():
    """
    Build byte strings like those generated by Tahoe-LAFS for use as HTTP API
    authorization tokens.
    """
    return binary(min_size=32, max_size=32).map(b64encode)


def ristretto_signing_keys():
    """
    Build byte strings holding base64-encoded Ristretto signing keys, perhaps
    with leading or trailing whitespace.
    """
    keys = sampled_from(
        [
            # A few legit keys
            b"mkQf85V2vyLQRUYuqRb+Ke6K+M9pOtXm4MslsuCdBgg=",
            b"6f93OIdZHHAmSIaRXDSIU1UcN+sbDAh41TRPb5DhrgI=",
            b"k58h8yPT18epw+EKMJhwHFfoM6r3TIExKm4efQHNBgM=",
            b"rbaAlWZ3NCnl5oZ9meviGfpLbyJpgpuiuFOX0rLnNwQ=",
        ]
    )
    whitespace = sampled_from(
        [
            # maybe no whitespace at all
            b""
            # or maybe some
            b" ",
            b"\t",
            b"\n",
            b"\r\n",
        ]
    )

    return builds(
        lambda leading, key, trailing: leading + key + trailing,
        whitespace,
        keys,
        whitespace,
    )