Cargo Features

generator-combinator has no features set by default.

[dependencies]
generator-combinator = { version = "0.4.0", features = ["with_rand"] }
with_rand = rand

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.

rand with_rand?