def is_lower_freq(freq1: str, freq2: str) -> bool:
    """Tests freq1 has a lower or equal frequency than freq2.
    Lower frequencies cannot be converted to higher frequencies
    due to lower resolution.

    Args:
        freq1: frequency 1
        freq2: frequency 2

    Returns:
        bool: frequency 1 is lower than or euqal to frequency 2
    """

    freq = ["H", "D", "B", "W", "M", "Q", "Y"]
    freq = dict(zip(freq, [*range(0, len(freq))]))

    return freq[freq1] >= freq[freq2]