code: func (t *BTTracer) PutDir(path string) error {
  	t.Logf(LogDebug, "Uploading snapshots from %s...\n", path)
  	return filepath.Walk(path, putDirWalk(t))
  }
docs: // Synchronously uploads snapshots contained in the specified directory.
  // It is safe to spawn a goroutine to run BTTracer.PutDir().
  //
  // ConfigurePut should have returned successfully before calling
  // BTTracer.PutDir().
  //
  // Only files with the '.btt' suffix will be uploaded.
  //
  // The first error encountered terminates the directory walk, thus
  // skipping snapshots which would have been processed later in the walk.