code: func (e *EnvProvider) Retrieve() (Value, error) {
  	e.retrieved = false
  
  	token := os.Getenv(EnvCredentialsVarToken)
  	if token == "" {
  		return Value{ProviderName: EnvCredentialsProviderName},
  			ErrEnvCredentialsTokenNotFound
  	}
  
  	e.retrieved = true
  	value := Value{
  		Token:        token,
  		Account:      os.Getenv(EnvCredentialsVarAccount),
  		ProviderName: EnvCredentialsProviderName,
  	}
  
  	return value, nil
  }
docs: // Retrieve retrieves the keys from the environment.