Returns a string after removing the appropriate words.

        If self.bow is false, replaces word with UNKWORDZ instead of removing
        it.

        Args:
            words_to_remove: list of ids (ints) to remove

        Returns:
            original raw string with appropriate words removed.

def inverse_removing(self, words_to_remove):
        """Returns a string after removing the appropriate words.

        If self.bow is false, replaces word with UNKWORDZ instead of removing
        it.

        Args:
            words_to_remove: list of ids (ints) to remove

        Returns:
            original raw string with appropriate words removed.
        """
        mask = np.ones(self.as_np.shape[0], dtype='bool')
        mask[self.__get_idxs(words_to_remove)] = False
        if not self.bow:
            return ''.join([self.as_list[i] if mask[i]
                            else 'UNKWORDZ' for i in range(mask.shape[0])])
        return ''.join([self.as_list[v] for v in mask.nonzero()[0]])