"One language only" is a marketing slogan. It's slightly misleading, since it doesn't look like you can implement meaningful applications in 100% Python or get

"One language only" is a marketing slogan. It's slightly misleading, since it doesn't look like you can implement meaningful applications in 100% Python or get away with zero knowledge of HTML and JS. But it may be close, like you can spend 90% of your development time on Python, and write JS components in the remaining 10%.