return True if ch is Chinese character.
    full-width puncts/latins are not counted in.

def is_zh(ch):
    """return True if ch is Chinese character.
    full-width puncts/latins are not counted in.
    """
    x = ord(ch)
    # CJK Radicals Supplement and Kangxi radicals
    if 0x2e80 <= x <= 0x2fef:
        return True
    # CJK Unified Ideographs Extension A
    elif 0x3400 <= x <= 0x4dbf:
        return True
    # CJK Unified Ideographs
    elif 0x4e00 <= x <= 0x9fbb:
        return True
    # CJK Compatibility Ideographs
    elif 0xf900 <= x <= 0xfad9:
        return True
    # CJK Unified Ideographs Extension B
    elif 0x20000 <= x <= 0x2a6df:
        return True
    else:
        return False