Setting up operation invoke (request)

[tpluscode]

The request input should be customisable in a given Invoke block. At least two options are necessary: body and headers.

Here's a possible structure, adding a second block for setting up the request a'la HTTP syntax

With Operation "CreateMovie" {
    Invoke {
        // headers like in HTTP
        Content-Type text/turtle

        // body in backticks like markdown
        ```
        <> a mov:Movie ; schema:title "Rocky 8" .
        ```
    } => {
        // response & representation checks
    }
}