title: How come Rust has trouble finding transitive dependencies?
body: <p>In Rust I'm getting the error during <code>cargo build</code>:</p>
  <pre><code> use tokio::net::{TcpListener, TcpStream};
       ^^^^^ use of undeclared crate or module `tokio`
  </code></pre>
  <p>even though I have</p>
  <pre><code>[dependencies]
  tokio-tungstenite = {version = &quot;0.17&quot;, features = [&quot;native-tls&quot;]}
  </code></pre>
  <p>and I can see the <code>tokio</code> in the <code>cargo tree</code></p>
  <pre><code>└── tokio-tungstenite v0.17.1
      ├── tokio v1.18.1
  
  </code></pre>
  <p>Is Rust not pulling in the transitive dependencies?  I thought it would.</p>