How to use the scrubadub.exceptions function in scrubadub

# get the text over lap correct
        if self.beg < other_filth.beg:
            first = self
            second = other_filth
        else:
            second = self
            first = other_filth
        end_offset = second.end - first.end
        if end_offset > 0:
            self.text = first.text + second.text[-end_offset:]

        # update the beg/end strings
        self.beg = min(self.beg, other_filth.beg)
        self.end = max(self.end, other_filth.end)
        if self.end - self.beg != len(self.text):
            raise exceptions.FilthMergeError("text length isn't consistent")

        # update the placeholder
        self.filths.append(other_filth)
        self._placeholder = '+'.join([filth.type for filth in self.filths])