def _parse_feature_string(s):
    features = []
    parts = s.split()
    i = 0
    length = len(parts)
    while i < length:
        feature = parts[i]
        if feature[0] in "0123456789":
            raise ValueError, "bad feature name: %r" % (feature,)
        i = i + 1
        version = None
        if i < length:
            v = parts[i]
            if "0123456789" in v[0]:
                i = i + 1
                version = v
        features.append((feature, version))
    return tuple(features)
dataset/ETHPy150Open deanhiller/databus/webapp/play1.3.x/python/Lib/xml/dom/domreg.py/_parse_feature_string/swapped operands of `in`