prow/slack/client.go
func NewClient(tokenGenerator func() []byte) *Client {
	return &Client{
		logger:         logrus.WithField("client", "slack"),
		tokenGenerator: tokenGenerator,
	}
}
func NewClient(tokenGenerator func() []byte) *Client {
	return &Client{
		logger:         logrus.WithField("client", "slack"),
		tokenGenerator: tokenGenerator,
	}
}
// NewClient creates a slack client with an API token.