Cargo Features

[dependencies]
stream_throttle = { version = "0.5.1", default-features = false, features = ["timer-tokio", "timer-futures-timer"] }
default = timer-tokio

The timer-tokio feature is set by default whenever stream_throttle is added without default-features = false somewhere in the dependency tree.

timer-tokio default = tokio
timer-futures-timer = futures-timer

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 timer-tokio
futures-timer timer-futures-timer?