def add_segment(self, segment):
        """\

        :param _Segment segment: Segment to add.
        """
        if self.segments:
            prev_seg = self.segments[-1]
            if prev_seg.mode == segment.mode and prev_seg.encoding == segment.encoding:
                # Merge segment with previous segment
                segment = _Segment(prev_seg.bits + segment.bits,
                                   prev_seg.char_count + segment.char_count,
                                   segment.mode, segment.encoding)
                self.bit_length -= len(prev_seg.bits)
                del self.segments[-1]
                del self.modes[-1]
        self.segments.append(segment)
        self.bit_length += len(segment.bits)
        self.modes.append(segment.mode)
\

        :param _Segment segment: Segment to add.