code: func EnvConfig() *Config {
  	config := &Config{}
  
  	if envPluginCacheDir := os.Getenv(pluginCacheDirEnvVar); envPluginCacheDir != "" {
  		// No Expandenv here, because expanding environment variables inside
  		// an environment variable would be strange and seems unnecessary.
  		// (User can expand variables into the value while setting it using
  		// standard shell features.)
  		config.PluginCacheDir = envPluginCacheDir
  	}
  
  	return config
  }
docs: // EnvConfig returns a Config populated from environment variables.
  //
  // Any values specified in this config should override those set in the
  // configuration file.