code: func (t *tOps) findKey(f *tFile, key []byte, ro *opt.ReadOptions) (rkey []byte, err error) {
  	ch, err := t.open(f)
  	if err != nil {
  		return nil, err
  	}
  	defer ch.Release()
  	return ch.Value().(*table.Reader).FindKey(key, true, ro)
  }
docs: // Finds key that is greater than or equal to the given key.