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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 merge(self, workdir, pot_files, out_dvdb, delete_source=True):
 """ Merge POT files containing 1st order DFPT potential return the absolute path of the new database in workdir. Args: delete_source: True if POT1 files should be removed after (successful) merge. """

        # We work with absolute paths.
        pot_files = [os.path.abspath(s) for s in list_strings(pot_files)]
        if not os.path.isabs(out_dvdb):
            out_dvdb = os.path.join(os.path.abspath(workdir), os.path.basename(out_dvdb))

        if self.verbose:
            print("Will merge %d files into output DVDB %s" % (len(pot_files), out_dvdb))
            for i, f in enumerate(pot_files):
                print(" [%d] %s" % (i, f))

        # Handle the case of a single file since mrgddb uses 1 to denote GS files!
        if len(pot_files) == 1:
            with open(pot_files[0], "r") as inh, open(out_dvdb, "w") as out:
                for line in inh:
                    out.write(line)
            return out_dvdb

        self.stdin_fname, self.stdout_fname, self.stderr_fname = \
            map(os.path.join, 3 * [os.path.abspath(workdir)], ["mrgdvdb.stdin", "mrgdvdb.stdout", "mrgdvdb.stderr"])

        inp = StringIO()
        inp.write(out_dvdb + "\n")             # Name of the output file.
        inp.write(str(len(pot_files)) + "\n")  # Number of input POT files.

        # Names of the POT files.
        for fname in pot_files:
            inp.write(fname + "\n")

        self.stdin_data = [s for s in inp.getvalue()]

        with open(self.stdin_fname, "wt") as fh:
            fh.writelines(self.stdin_data)
            # Force OS to write data to disk.
            fh.flush()
            os.fsync(fh.fileno())

        retcode = self.execute(workdir)
        if retcode == 0 and delete_source:
            # Remove pot files.
            for f in pot_files:
                try:
                    os.remove(f)
                except IOError:
                    pass

        return out_dvdb