code: func (lcs *lcs) LengthContext(ctx context.Context) (length int, err error) {
  	table, err := lcs.TableContext(ctx)
  	if err != nil {
  		return 0, err
  	}
  	return table[len(lcs.left)][len(lcs.right)], nil
  }
docs: // Table implements Lcs.LengthContext()