- One-off error messages can be constructed using the `anyhow!` macro, which
  supports string interpolation and produces an `anyhow::Error`.

  ```rust
  return Err(anyhow!("missing attribute: {}", missing));
  ```

//!
//! - One-off error messages can be constructed using the `anyhow!` macro, which
//!   supports string interpolation and produces an `anyhow::Error`.

//!   ```
//!   # use anyhow::{anyhow, Result};
//!   #
//!   # fn demo() -> Result<()> {
//!   #     let missing = "...";
//!   return Err(anyhow!("missing attribute: {}", missing));
//!   #     Ok(())
//!   # }
//!   ```
//!