code: def encrypt(
      ek: EncryptionKey,
      plaintext: tf.Tensor,
      randomness: Optional[Randomness] = None,
  ) -> Ciphertext:
      x = tf_big.import_tensor(plaintext)
  
      randomness = randomness or gen_randomness(ek=ek, shape=x.shape)
      r = randomness.raw
      assert r.shape == x.shape
  
      gx = 1 + (ek.n * x) % ek.nn
      rn = tf_big.pow(r, ek.n, ek.nn)
      c = gx * rn % ek.nn
      return Ciphertext(ek, c)
  
imports: from typing import Optional
  from typing import Tuple
  import tensorflow
  import tf_big
label_desc: Use image node_id 5 for calling a global function with example usage: encrypt(ek, plaintext, randomness) and returns: Ciphertext