code: func (c *Scratch) SetInMap(key string, mapKey string, value interface{}) string {
  	c.mu.Lock()
  	_, found := c.values[key]
  	if !found {
  		c.values[key] = make(map[string]interface{})
  	}
  
  	c.values[key].(map[string]interface{})[mapKey] = value
  	c.mu.Unlock()
  	return ""
  }
docs: // SetInMap stores a value to a map with the given key in the Node context.
  // This map can later be retrieved with GetSortedMapValues.