make example fails on ubuntu 18.04 with go1.15.2

[davidcoble]

$ make example
... don't know if you want the full output here ...
**./demo.go:265:51: cannot use map[string]string literal (type map[string]string) as type map[string]interface {} in argument to buffer.CreateTag**
_example/example.mk:35: recipe for target '_example/demo/demo' failed
make: *** [_example/demo/demo] Error 2

[gharabakloo]

I have fixed it in #418