docs: def create_ondemand_streaming_locator(access_token, encoded_asset_id, pid, starttime=None):
      '''Create Media Service OnDemand Streaming Locator.
  
      Args:
          access_token (str): A valid Azure authentication token.
          encoded_asset_id (str): A Media Service Encoded Asset ID.
          pid (str): A Media Service Encoded PID.
          starttime (str): A Media Service Starttime.
  
      Returns:
          HTTP response. JSON body.
      '''
      path = '/Locators'
      endpoint = ''.join([ams_rest_endpoint, path])
      if starttime is None:
          body = '{ \
  			"AccessPolicyId":"' + pid + '", \
  			"AssetId":"' + encoded_asset_id + '", \
  			"Type": "2" \
      }'
      else:
          body = '{ \
  			"AccessPolicyId":"' + pid + '", \
  			"AssetId":"' + encoded_asset_id + '", \
  			"StartTime":"' + str(starttime) + '", \
  			"Type": "2" \
  		}'
      return do_ams_post(endpoint, path, body, access_token, "json_only")