def _get_block(self, subset, text, offsets_start):
        """
        Retrieve the annotated text, annotations are contained in subset
        @type subset: C{list}
        @param subset: list of annotation offset pairs
        @type text: C{str}
        @param text: text read from text stream
        @type offsets_start: C{int}
        @param offset_start: integer to correct for discrepency 
                            between offsets and text character number
        @return: list of annotated text
        @rtype: C{list} of C{str} 
        """
        block = []
        for s in subset:
            start = s[0] - offsets_start
            end = offsets_start - s[1]
            chunk = text[start:end].encode('utf-8')
            chunk = self._remove_ws(chunk)
            block.append(chunk)
        return block
dataset/ETHPy150Open cidles/graf-python/nltk/masc.py/MascCorpusReader._get_block/swapped operands of `-`