So, what we will do next is add the code to document how that *external API* should look like to receive the callback from *your API*.

That documentation will show up in the Swagger UI at `/docs` in your API, and it will let external developers know how to build the *external API*.

This example doesn't implement the callback itself (that could be just a line of code), only the documentation part.

// The returned list of actions may be incomplete depending on the server's authorization mode,
// and any errors experienced during the evaluation. SelfSubjectRulesReview should be used by UIs to show/hide actions,
// or to quickly let an end user reason about their permissions. It should NOT Be used by external systems to

    }

    // -----------------------------------------------------
    //                                     Parameter Logging
    //                                     -----------------
    // logging filter cannot show the parameters when multi-part so logging here
    protected void showFieldLoggingTitle() {
        if (logger.isDebugEnabled()) {
            logger.debug("[Multipart Request Parameter]");
        }
    }

rflow[1],o.overflowY=c.overflow[2]}));for(d in b)if(e=b[d],Nb.exec(e)){if(delete b[d],f=f||"toggle"===e,e===(p?"hide":"show")){if("show"!==e||!q||void 0===q[d])continue;p=!0}m[d]=q&&q[d]||n.style(a,d)}else j=void 0;if(n.isEmptyObject(m))"inline"===("none"===j?tb(a.nodeName):j)&&(o.display=j);else{q?"hidden"in q&&(p=q.hidden):q=L.access(a,"fxshow",{}),f&&(q.hidden=!p),p?n(a).show():l.done(function(){n(a).hide()}),l.done(function(){var b;L.remove(a,"fxshow");for(b in m)n.style(a,b,m[b])});for(d in...

---

"_I’m over the moon excited about **FastAPI**. It’s so fun!_"

<div style="text-align: right; margin-right: 10%;">Brian Okken - <strong><a href="https://pythonbytes.fm/episodes/show/123/time-to-right-the-py-wrongs?time_in_sec=855" target="_blank">Python Bytes</a> podcast host</strong> <a href="https://twitter.com/brianokken/status/1112220079972728832" target="_blank"><small>(ref)</small></a></div>

---

				field.Schema.DeleteClauses = append(field.Schema.DeleteClauses, fc.DeleteClauses(field)...)
			}
		}
	}

	return schema, schema.err
}

// This unrolling is needed to show to the compiler the exact set of methods
// that can be used on the modelType.
// Prior to go1.22 any use of MethodByName would cause the linker to
// abandon dead code elimination for the entire binary.

### Include a *path operation*

We can also add *path operations* directly to the `FastAPI` app.

Here we do it... just to show that we can 🤷:

```Python hl_lines="21-23" title="app/main.py"
{!../../docs_src/bigger_applications/app/main.py!}
```

round:"pink",color:"#FF0000",fontWeight:"bold",border:"red solid 1px",borderWidth:"0px 0px 4px",display:"inline-block",fontSize:d.fontSize,padding:d.padding},h=d.bad;0===e.length&&(e=a("<span></span>"),e.addClass("strength-meter").appendTo(c)),b?e.show():e.hide(),1===f?h=d.weak:2===f?(g.background="lightyellow",g.borderColor="yellow",g.color="goldenrod",h=d.good):f>=3&&(g.background="lightgreen",g.borderColor="darkgreen",g.color="darkgreen",h=d.strong),e.css(g).text(h)})}});var f=function(b,c,d,e,f){var...

You can see it directly at: <a href="http://127.0.0.1:8000/openapi.json" class="external-link" target="_blank">http://127.0.0.1:8000/openapi.json</a>.

It will show a JSON starting with something like:

```JSON
{
    "openapi": "3.1.0",
    "info": {
        "title": "FastAPI",
        "version": "0.1.0"
    },
    "paths": {
        "/items/": {

// The returned list of actions may be incomplete depending on the server's authorization mode,
// and any errors experienced during the evaluation. SelfSubjectRulesReview should be used by UIs to show/hide actions,
// or to quickly let an end user reason about their permissions. It should NOT Be used by external systems to