code: func SignChannelConfig(ctx context.Client, config []byte, signer msp.SigningIdentity) (*common.ConfigSignature, error) {
  	logger.Debug("SignChannelConfig - start")
  
  	if config == nil {
  		return nil, errors.New("channel configuration required")
  	}
  
  	signingUser := signer
  	// If signing user is not provided default to client's user context
  	if signingUser == nil {
  		signingUser = ctx
  	}
  
  	if signingUser == nil {
  		return nil, errors.New("user context required")
  	}
  
  	sigCtx := fabCtx{
  		Providers:       ctx,
  		SigningIdentity: signingUser,
  	}
  
  	return CreateConfigSignature(sigCtx, config)
  }
docs: // SignChannelConfig signs a configuration.