code: public Observable<InputStream> getFromComputeNodeAsync(String poolId, String nodeId, String filePath) {
          return getFromComputeNodeWithServiceResponseAsync(poolId, nodeId, filePath).map(new Func1<ServiceResponseWithHeaders<InputStream, FileGetFromComputeNodeHeaders>, InputStream>() {
              @Override
              public InputStream call(ServiceResponseWithHeaders<InputStream, FileGetFromComputeNodeHeaders> response) {
                  return response.body();
              }
          });
      }
docs: Returns the content of the specified compute node file.
  
  @param poolId The ID of the pool that contains the compute node.
  @param nodeId The ID of the compute node that contains the file.
  @param filePath The path to the compute node file that you want to get the content of.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the InputStream object