code: func (m MapClaims) VerifyExpiresAt(cmp int64, req bool) bool {
  	switch exp := m["exp"].(type) {
  	case float64:
  		return verifyExp(int64(exp), cmp, req)
  	case json.Number:
  		v, _ := exp.Int64()
  		return verifyExp(v, cmp, req)
  	}
  	return req == false
  }
docs: // Compares the exp claim against cmp.
  // If required is false, this method will return true if the value matches or is unset