from typing import List


def selfies_alphabet() -> List[str]:
    """Legacy selfies 0.2.4 alphabet method.

    Adapted from: https://github.com/aspuru-guzik-group/selfies/blob/84122855ae76a928e1cb7d58796b8b47385a4359/selfies/selfies.py#L4.

    Returns:
        SELFIES list of tokens.
    """
    alphabet = [
        "[Branch1_1]",
        "[Branch1_2]",
        "[Branch1_3]",
        "[Ring1]",
        "[Branch2_1]",
        "[Branch2_2]",
        "[Branch2_3]",
        "[Ring2]",
        "[Branch3_1]",
        "[Branch3_2]",
        "[Branch3_3]",
        "[Ring3]",
        "[O]",
        "[=O]",
        "[N]",
        "[=N]",
        "[C]",
        "[=C]",
        "[#C]",
        "[S]",
        "[=S]",
        "[P]",
        "[F]",
        "[C@Hexpl]",
        "[C@@Hexpl]",
        "[C@expl]",
        "[C@@expl]",
        "[H]",
        "[NHexpl]",
    ]
    return alphabet