code: def sign_hmac(secret, payload):
      
      payload = payload.encode('ascii', 'strict')
      secret = secret.encode('ascii', 'strict')
      sig = hmac.new(base64.urlsafe_b64decode(secret), payload, hashlib.sha1)
      out = base64.urlsafe_b64encode(sig.digest())
      return out.decode('utf-8')
docs: Returns a base64-encoded HMAC-SHA1 signature of a given string.
  
      :param secret: The key used for the signature, base64 encoded.
      :type secret: string
  
      :param payload: The payload to sign.
      :type payload: string
  
      :rtype: string