The simplest gtag app could look like this

from gtag import GTag, Tag

class Comp(GTag):
    size=(200,100)
    def build(self):
        return Tag.span("hello world")

app=Comp()
app.run()

Will produce (on Ubuntu 20.04)

Important

• Here ... the build() method return a Tag. (but it exactly the same rendering that the previous example)
• the build() method is called at each rendering time.