Cargo Features

Lease has no features set by default.

[dependencies]
lease = { version = "0.5.2", features = ["async"] }
async = futures-channel, futures-core

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.

futures-core async?
futures-channel async?