def _parse_CHANLIMIT(value):
        """
        >>> res = FeatureSet._parse_CHANLIMIT('ibe:250,xyz:100')
        >>> len(res)
        6
        >>> res['x']
        100
        >>> res['i'] == res['b'] == res['e'] == 250
        True
        """
        pairs = map(string_int_pair, value.split(','))
        return dict(
            (target, number)
            for target_keys, number in pairs
            for target in target_keys
        )
>>> res = FeatureSet._parse_CHANLIMIT('ibe:250,xyz:100')
        >>> len(res)
        6
        >>> res['x']
        100
        >>> res['i'] == res['b'] == res['e'] == 250
        True