Cargo Features

line_2d has no features set by default.

[dependencies]
line_2d = { version = "0.5.3", features = ["serialize"] }
serialize = serde

Enables serialize of coord_2d and direction

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 serialize?