code: def crypto_sign(msg, sk):
      
      if len(sk) != SECRETKEYBYTES:
          raise ValueError("Bad signing key length %d" % len(sk))
      vkbytes = sk[PUBLICKEYBYTES:]
      skbytes = sk[:PUBLICKEYBYTES]
      sig = djbec.signature(msg, skbytes, vkbytes)
      return sig + msg
docs: Return signature+message given message and secret key.
      The signature is the first SIGNATUREBYTES bytes of the return value.
      A copy of msg is in the remainder.