$ cat serde_json.rs
//# serde_json = "*"

use serde_json::{Result, Value};

fn main() -> Result<()> {
    // Some JSON input data as a &str. Maybe this comes from the user.
    let data = r#"
        {
            "name": "John Doe",
            "age": 43,
            "phones": [
                "+44 1234567",
                "+44 2345678"
            ]
        }"#;

    // Parse the string of data into serde_json::Value.
    let v: Value = serde_json::from_str(data)?;

    // Access parts of the data by indexing with square brackets.
    println!("Please call {} at the number {}", v["name"], v["phones"][0]);

    Ok(())
}

$ cargo play serde_json.rs
    Updating crates.io index
   Compiling serde v1.0.91
   Compiling ryu v0.2.8
   Compiling itoa v0.4.4
   Compiling serde_json v1.0.39
   Compiling gvzcg8yviqmd_euq3xti4-zbkrs v0.1.0 (/var/folders/nq/608n9lcx02n_mzx33_3z5wyw0000gn/T/cargo-play.GVzCg8yviQmd_EUq3Xti4-ZbKRs)
    Finished dev [unoptimized + debuginfo] target(s) in 10.23s
     Running `/var/folders/nq/608n9lcx02n_mzx33_3z5wyw0000gn/T/cargo-play.GVzCg8yviQmd_EUq3Xti4-ZbKRs/target/debug/gvzcg8yviqmd_euq3xti4-zbkrs`
Please call "John Doe" at the number "+44 1234567"

$ cat tests/multi/entry.rs
mod hello;

fn main() {
    println!("Hello {}", hello::world());
}
$ cat tests/multi/hello.rs
pub fn world() -> String {
    "World".into()
}
$ cargo play tests/multi/*
   Compiling qvsjdw04fxh5cgpdkdvg6ite_ak v0.1.0 (/var/folders/nq/608n9lcx02n_mzx33_3z5wyw0000gn/T/cargo-play.QVSJDw04FxH5CGpDkDvg6itE_ak)
    Finished dev [unoptimized + debuginfo] target(s) in 0.30s
     Running `/var/folders/nq/608n9lcx02n_mzx33_3z5wyw0000gn/T/cargo-play.QVSJDw04FxH5CGpDkDvg6itE_ak/target/debug/qvsjdw04fxh5cgpdkdvg6ite_ak`
Hello World