Marker trait for types that mark a part of a URI.
This trait exists solely to categorize types that mark a part of the URI,
Query. Said another way, types that implement
this trait are marker types that represent a part of a URI at the
This trait is sealed: it cannot be implemented outside of Rocket.
You will find this trait in traits like
UriDisplay or structs like
Formatter as the bound on a generic parameter:
P: UriPart. Because the
trait is sealed, the generic type is guaranteed to be instantiated as one of
Path, effectively creating two instances of the generic
Formatter<Path>. Unlike having two distinct, non-generic traits, this
approach enables succinct, type-checked generic implementations of these