Cargo is a tool that allows Rust projects to declare their various
 dependencies, and ensure that you'll always get a repeatable build.
 .
 To accomplish this goal, Cargo does four things:
  * Introduces two metadata files with various bits of project information.
  * Fetches and builds your project's dependencies.
  * Invokes rustc or another build tool with the correct parameters to build
    your project.
  * Introduces conventions, making working with Rust projects easier.
 .
 Cargo downloads your Rust project’s dependencies and compiles your
 project.