code: def add(
      ek: EncryptionKey,
      lhs: Ciphertext,
      rhs: Ciphertext,
      do_refresh: bool = True,
  ) -> Ciphertext:
      c0 = lhs.raw
      c1 = rhs.raw
      c = (c0 * c1) % ek.nn
      res = Ciphertext(ek, c)
  
      if not do_refresh:
          return res
      return refresh(ek, res)
  
imports: from typing import Optional
  from typing import Tuple
  import tensorflow
  import tf_big
label_desc: Use image node_id 8 for calling a global function with example usage: add(ek, lhs, rhs, do_refresh) and returns: refresh, res