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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def to_sint(self):
 """Converts the word to a BinInt, treating it as a signed number."""

        if self._width == 0:
            return BinInt(0)
        sbit = 1 << (self._width - 1)
        return BinInt((self._val - sbit) ^ -sbit)