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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 _expand_sequence(self, seq: List[GridQubit]) -> List[GridQubit]: """Tries to expand given sequence with more qubits. Args: seq: Linear sequence of qubits. Returns: New continuous linear sequence which contains all the qubits from seq and possibly new qubits inserted in between. """

        i = 1
        while i < len(seq):
            path = self._find_path_between(seq[i - 1], seq[i], set(seq))
            if path:
                seq = seq[:i] + path + seq[i:]
            else:
                i += 1
        return seq