def movemessage(self, n, tofolder, ton):
        """Move one message over a specific destination message,
        which may or may not already exist."""
        path = self.getmessagefilename(n)
        # Open it to check that it exists
        f = open(path)
        f.close()
        del f
        topath = tofolder.getmessagefilename(ton)
        backuptopath = tofolder.getmessagefilename(',%d' % ton)
        try:
            os.rename(topath, backuptopath)
        except os.error:
            pass
        try:
            os.rename(path, topath)
        except os.error:
            # Try copying
            ok = 0
            try:
                tofolder.setlast(None)
                shutil.copy2(path, topath)
                ok = 1
            finally:
                if not ok:
                    try:
                        os.unlink(topath)
                    except os.error:
                        pass
            os.unlink(path)
        self.removefromallsequences([n])
dataset/ETHPy150Open Southpaw-TACTIC/TACTIC/src/context/client/tactic-api-python-4.0.api04/Lib/mhlib.py/Folder.movemessage/original