code: func (p *parser) recover(errp *error) {
  	e := recover()
  	if _, ok := e.(runtime.Error); ok {
  		// Print the stack trace but do not inhibit the running application.
  		buf := make([]byte, 64<<10)
  		buf = buf[:runtime.Stack(buf, false)]
  
  		fmt.Fprintf(os.Stderr, "parser panic: %v\n%s", e, buf)
  		*errp = errUnexpected
  	} else if e != nil {
  		*errp = e.(error)
  	}
  	p.lex.close()
  }
docs: // recover is the handler that turns panics into returns from the top level of Parse.