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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 Encrypt(self, data, iv=None):
 """Symmetrically encrypt the data using the optional iv."""

    if iv is None:
      iv = rdf_crypto.EncryptionKey.GenerateKey(length=128)
    cipher = rdf_crypto.AES128CBCCipher(self.cipher.key, iv)
    return iv, cipher.Encrypt(data)