code: protected OkRequest<T> copy(final InputStream input, final OutputStream output) throws IOException {
          return new CloseOperation<OkRequest>(input, mIgnoreCloseExceptions) {
  
              @Override
              public OkRequest<T> call() throws IOException {
                  boolean thrown = false;
                  try {
                      final byte[] buffer = new byte[mBufferSize];
                      int read;
                      while ((read = input.read(buffer)) != -1) {
                          output.write(buffer, 0, read);
                      }
                      return OkRequest.this;
                  } catch (IOException e) {
                      thrown = true;
                      throw e;
                  } finally {
                      try {
                          done();
                      } catch (IOException e) {
                          if (!thrown) {
                              throw e;
                          }
                      }
  
                  }
  
              }
          }.call();
      }
docs: Copy from input stream to output stream
  
  @param input
  @param output
  @return this request
  @throws java.io.IOException