code: def crypto_sign_keypair(seed=None):
      
      if seed is None:
          seed = os.urandom(PUBLICKEYBYTES)
      else:
          warnings.warn("ed25519ll should choose random seed.",
                        RuntimeWarning)
      if len(seed) != 32:
          raise ValueError("seed must be 32 random bytes or None.")
      skbytes = seed
      vkbytes = djbec.publickey(skbytes)
      return Keypair(vkbytes, skbytes+vkbytes)
docs: Return (verifying, secret) key from a given seed, or os.urandom(32)