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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 read(cls, five9, external_id):
 """Return a record singleton for the ID. Args: five9 (five9.Five9):
 The authenticated Five9 remote. external_id (mixed):
 The identified on Five9. This should be the value that is in the ``__uid_field__`` field on the record. Returns: BaseModel: The record, if found. Otherwise ``None`` """

        results = cls.search(five9, {cls.__uid_field__: external_id})
        if not results:
            return None
        return results[0]