def _parse_decay_mode_label(mode: str) -> str:
    """
    Format a decay mode string for edge label on decay chain plot.

    Parameters
    ----------
    mode : str
        Decay mode string.

    Returns
    -------
    str
        Formatted decay mode string for use in an edge label.

    """

    mode_conversion = {
        "α": "\N{GREEK SMALL LETTER ALPHA}",
        "β": "\N{GREEK SMALL LETTER BETA}",
        "+": "\N{SUPERSCRIPT PLUS SIGN}",
        "-": "\N{SUPERSCRIPT MINUS}",
    }

    for unformatted, formatted in mode_conversion.items():
        mode = mode.replace(unformatted, formatted)
    return mode