Cargo Features

diffeq has no features set by default.

[dependencies]
diffeq = { version = "0.1.0", features = ["serde0"] }
serde0 = serde

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.

serde serde0?