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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 preprocess(self):
 """ Run preprocessor on a top-level file. Performs the following preprocess steps: - Expand `include directives - Perl Preprocessor Returns ------- tuple (preprocessed_text, SegmentMap) """

        tokens = self.tokenize()
        pl_segments, has_perl_tags = self.get_perl_segments(tokens)

        # Generate flattened output
        str_parts = []
        smap = segment_map.SegmentMap()
        offset = 0

        if has_perl_tags:
            # Needs to be processed through perl interpreter
            emit_list = self.run_perl_miniscript(pl_segments)

            for entry in emit_list:
                if entry['type'] == "ref":
                    pl_seg = pl_segments[entry['ref']]
                    emit_text = pl_seg.get_text()

                    map_seg = segment_map.UnalteredSegment(
                        offset, offset + len(emit_text) - 1,
                        pl_seg.start, pl_seg.end, pl_seg.file_pp.path,
                        pl_seg.file_pp.incl_ref
                    )
                    offset += len(emit_text)
                    smap.segments.append(map_seg)
                    str_parts.append(emit_text)

                elif entry['type'] == "text":
                    pl_seg = pl_segments[entry['ref']]
                    emit_text = entry['text']

                    map_seg = segment_map.MacroSegment(
                        offset, offset + len(emit_text) - 1,
                        pl_seg.start, pl_seg.end, pl_seg.file_pp.path,
                        pl_seg.file_pp.incl_ref
                    )
                    offset += len(emit_text)
                    smap.segments.append(map_seg)
                    str_parts.append(emit_text)
        else:
            # OK to bypass perl interpreter
            for pl_seg in pl_segments:
                emit_text = pl_seg.get_text()
                map_seg = segment_map.UnalteredSegment(
                    offset, offset + len(emit_text) - 1,
                    pl_seg.start, pl_seg.end, pl_seg.file_pp.path,
                    pl_seg.file_pp.incl_ref
                )
                offset += len(emit_text)
                smap.segments.append(map_seg)
                str_parts.append(emit_text)

        #segment_map.print_segment_debug("".join(str_parts), smap)

        return ("".join(str_parts), smap)