Finds the maximum length of a single betacode token.

    Returns:
    The length of the longest key in the betacode map, which corresponds to the
    longest single betacode token.

def _find_max_beta_token_len():
    """
    Finds the maximum length of a single betacode token.

    Returns:
    The length of the longest key in the betacode map, which corresponds to the
    longest single betacode token.
    """
    max_beta_len = -1
    for beta, uni in _map.BETACODE_MAP.items():
        if len(beta) > max_beta_len:
            max_beta_len = len(beta)

    return max_beta_len