code: func (c *ConfigFile) MustBool(section, key string, defaultVal ...bool) bool {
  	val, err := c.Bool(section, key)
  	if len(defaultVal) > 0 && err != nil {
  		return defaultVal[0]
  	}
  	return val
  }
docs: // MustBool always returns value without error,
  // it returns false if error occurs.