If you call

sender, err := senders.NewSender("https://11111111-2222-3333-4444-555555555555@surf.wavefront.com")

To get a sender that does direct ingestion to https://surf.wavefront.com, it won't work because it tries to send to port 2878 instead of to port 443.

If you call

sender, err := senders.NewSender("https://11111111-2222-3333-4444-555555555555@surf.wavefront.com:443")

This does work, but a user of the API will not think to do this.

This API should be intuitive for users. Both chunks of code ought to work.