'Return self + (-other)'

def __sub__(self, other, context=None):

    other = _convert_other(other)
    if (self._is_special or other._is_special):
        ans = self._check_nans(other, context=context)
        if ans:
            return ans
    tmp = Decimal(other)
    tmp._sign = (1 - tmp._sign)
    return self.__add__(tmp, context=context)
