code: func (cfgSrcHandler *Handler) GetConfigurationByKey(key string) (interface{}, error) {
  	cfgSrcHandler.Lock()
  	configSrcVal, ok := cfgSrcHandler.Configurations[key]
  	cfgSrcHandler.Unlock()
  	if ok {
  		return configSrcVal, nil
  	}
  
  	return nil, errors.New("key not exist")
  }
docs: //GetConfigurationByKey gets required configuration for a particular key