Features from optional dependencies

async-std implicit feature

Enables async-std

async-std:

Async version of the Rust standard library

Affects runtime::AsyncStdRuntime

serde implicit feature

Enables serde

serde:

A generic serialization/deserialization framework

tokio implicit feature

Enables tokio

tokio:

An event-driven, non-blocking I/O platform for writing asynchronous I/O backed applications

version-ranges implicit feature

Enables version-ranges

version-ranges:

Performance-optimized type for generic version ranges and operations on them