def buildHeaderString(keys):
  """
  Use authentication keys to build a literal header string that will be
  passed to the API with every call.
  """
  headers = {
    # Request headers
    'participant-key': keys["participantKey"],
    'Content-Type': 'application/json',
    'Ocp-Apim-Subscription-Key': keys["subscriptionKey"]
  }
  return headers