def erized(syllable: str) -> bool:
    """Whether the syllable contains erhua effect.
    
    Example
    --------
    huar -> True
    guanr -> True
    er -> False
    """
    # note: for pinyin, len(syllable) >=2 is always true
    # if not: there is something wrong in the data
    assert len(syllable) >= 2, f"inavlid syllable {syllable}"
    return syllable[:2] != "er" and syllable[-2] == 'r'