code: def generate_request_access_signature(parameters, secret_key):
      
      # pull out the parameter keys
      keys = parameters.keys()
  
      # alphanumerically sort the keys in place
      keys.sort()
  
      # create an array of url encoded key:value pairs
      encoded_pairs = [urlencode({key: parameters[key]}) for key in keys]
  
      # create the serialized parameters in a single, URL style string
      serialized_parameters = '&'.join(encoded_pairs)
  
      # create the string with the secret key and the parameters which will be hashed
      string_to_hash = '%s:%s' % (secret_key, serialized_parameters)
  
      # return the hex digest of the hashed string
      return sha256(string_to_hash).hexdigest()
docs: Generate the parameter signature used during third party access requests