Cargo Features

ws_stream_tungstenite has no features set by default.

ws_stream_tungstenite = { version = "0.13.0", features = ["tokio_io"] }
tokio_io = tokio

Enables tokio_io of async_io_stream

Features from optional dependencies

In crates that don't use the dep: syntax, optional dependencies automatically become Cargo features. These features may have been created by mistake, and this functionality may be removed in the future.

tokio tokio_io?