But then we get a `dict` in the parameter `commons` of the *path operation function*.

And we know that editors can't provide a lot of support (like completion) for `dict`s, because they can't know their keys and value types.

We can do better...

## What makes a dependency { #what-makes-a-dependency }

Up to now you have seen dependencies declared as functions.

     *   <li>If this field's value is some other thread object, we know that it's not our thread.
     *   <li>If this field's value == null because it originally belonged to another thread and that
     *       thread cleared it, we still know that it's not associated with our thread
     *   <li>If this field's value == null because it was associated with our thread and was
     *       cleared, we know that we're not executing inline any more
     * </ul>

{* ../../docs_src/dependencies/tutorial005_an_py310.py hl[23] *}

/// info

Notice that we are only declaring one dependency in the *path operation function*, the `query_or_cookie_extractor`.

But **FastAPI** will know that it has to solve `query_extractor` first, to pass the results of that to `query_or_cookie_extractor` while calling it.

///

```mermaid
graph TB

query_extractor(["query_extractor"])

When using a proxy to handle HTTPS, your **application server** (for example Uvicorn via FastAPI CLI) doesn't known anything about the HTTPS process, it communicates with plain HTTP with the **TLS Termination Proxy**.

This **proxy** would normally set some HTTP headers on the fly before transmitting the request to the **application server**, to let the application server know that the request is being **forwarded** by the proxy.

/// note | Technical Details

**FastAPI** will know that it can use the class `OAuth2PasswordBearer` (declared in a dependency) to define the security scheme in OpenAPI because it inherits from `fastapi.security.oauth2.OAuth2`, which in turn inherits from `fastapi.security.base.SecurityBase`.

All the security utilities that integrate with OpenAPI (and the automatic API docs) inherit from `SecurityBase`, that's how **FastAPI** can know how to integrate them in OpenAPI.

## Tweet about **FastAPI** { #tweet-about-fastapi }

[Tweet about **FastAPI**](https://x.com/compose/tweet?text=I'm loving @fastapi because... https://github.com/fastapi/fastapi) and let me and others know why you like it. 🎉

I love to hear about how **FastAPI** is being used, what you have liked in it, in which project/company are you using it, etc.

## Vote for FastAPI { #vote-for-fastapi }

    if (mapEntryBelowToTruncate != null) {
      // we know ( [
      RangeMapEntry<K, V> rangeMapEntry = mapEntryBelowToTruncate.getValue();
      if (rangeMapEntry.getUpperBound().compareTo(rangeToRemove.lowerBound) > 0) {
        // we know ( [ )
        if (rangeMapEntry.getUpperBound().compareTo(rangeToRemove.upperBound) > 0) {
          // we know ( [ ] ), so insert the range ] ) back into the map --

	// other fields such as expiry etc.
	return claims.Valid()
}

// ParseUnverifiedStandardClaims - WARNING: Don't use this method unless you know what you're doing
//
// This method parses the token but doesn't validate the signature. It's only
// ever useful in cases where you know the signature is valid (because it has
// been checked previously in the stack) and you want to extract values from
// it.

   
   *Please let us know if this helps.*
   
windows_comment: >
   From the stack trace it looks like you are hitting windows path length limit.
      * Try to disable path length limit on Windows 10.
        * Refer [disable path length limit instructions guide.](https://mspoweruser.com/ntfs-260-character-windows-10/)
   

/// note

Some response codes (see the next section) indicate that the response does not have a body.

FastAPI knows this, and will produce OpenAPI docs that state there is no response body.

///

## About HTTP status codes { #about-http-status-codes }

/// note

If you already know what HTTP status codes are, skip to the next section.

///