Macro dependencies 

dependencies!() { /* proc-macro */ }

This macro generates code from a Spin components dependencies using wit-bindgen. During expansion the macro will check for existence of a spin-dependencies.wit in the developers project directory and if it is present (used to indicate the presence of dependencies in the manifest) will invoke wit-bindgen to generate the bindings.

use spin_sdk::http::{Request, IntoResponse};
use spin_sdk::http_service;

// Optionally generate dependencies if "spin-dependencies.wit" is present.
spin_sdk::dependencies!();

#[http_service]
async fn my_handler(request: Request) -> impl IntoResponse {
  // Your logic goes here
}