code: function xivelyPost(feedId, streamId, apiKey, currentValue) {
      var dataPoint =
      {
          "version":"1.0.0",
          "datastreams" :
          [
              {
                  "id" : streamId,
                  "current_value" : currentValue
              },
          ]
      };
  
      var requestUrl = "https://api.xively.com/v2/feeds/" + feedId;
  
      var options = {
          url: requestUrl,
          headers: {
              "X-ApiKey" : apiKey,
              "Content-Type": "application/json",
              "Accept": "*/*",
              "User-Agent": "nodejs"
          },
          body: JSON.stringify(dataPoint)
      };
  
      return requestPut(options);
  }
docs: Creates a new observable that will make a HTTP or HTTPS POST request to the given url and will give the results as a single event in the stream.