code: func (logger *Logger) GetStaticFields() map[string]interface{} {
  	var wasErr error
  	staticFieldsMap := make(map[string]interface{})
  
  	logger.staticFields.Range(func(k, v interface{}) bool {
  		key, ok := k.(string)
  		if !ok {
  			wasErr = fmt.Errorf("cannot cast log map key to string")
  			// false stops the iteration
  			return false
  		}
  		staticFieldsMap[key] = v
  		return true
  	})
  
  	// throw panic outside of logger.Range()
  	if wasErr != nil {
  		panic(wasErr)
  	}
  
  	return staticFieldsMap
  }
docs: // GetStaticFields returns currently set map of static fields - key-value pairs
  // that are automatically added into log entry