code: def _sign_data(secret, data):
      
      sha1_hash = hmac.new(secret.encode(), data.encode(), sha1)
      return binascii.b2a_base64(sha1_hash.digest())[:-1].decode('utf8')
docs: Sign data.
  
      :param data: the string to sign
      :return: string base64 encoding of the HMAC-SHA1 hash of the data parameter using {@code secretKey} as cipher key.