* Automatic and clear errors when the data is invalid.
    * Validation even for deeply nested JSON objects.
* <abbr title="also known as: serialization, parsing, marshalling">Conversion</abbr> of input data: coming from the network to Python data and types. Reading from:
    * JSON.
    * Path parameters.
    * Query parameters.
    * Cookies.
    * Headers.
    * Forms.
    * Files.

    return burgers
```

With `async def`, Python knows that, inside that function, it has to be aware of `await` expressions, and that it can "pause" ⏸ the execution of that function and go do something else 🔀 before coming back.

When you want to call an `async def` function, you have to "await" it. So, this won't work:

```Python
# This won't work, because get_burgers was defined with: async def
burgers = get_burgers(2)
```

You will get completion in code you might even consider impossible before. As for example, the `price` key inside a JSON body (that could have been nested) that comes from a request.

No more typing the wrong key names, coming back and forth between docs, or scrolling up and down to find if you finally used `username` or `user_name`.

### Short { #short }

And be compatible with all of them at the same time.

///

Create a utility function to hash a password coming from the user.

And another utility to verify if a received password matches the hash stored.

And another one to authenticate and return a user.

  Either the well was very deep, or she fell very slowly, for she
had plenty of time as she went down to look about her and to
wonder what was going to happen next.  First, she tried to look
down and make out what she was coming to, but it was too dark to
see anything; then she looked at the sides of the well, and
noticed that they were filled with cupboards and book-shelves;
here and there she saw maps and pictures hung upon pegs.  She

* **Define requirements**: from request path parameters, query parameters, headers, bodies, dependencies, etc.
* **Convert data**: from the request to the required type.
* **Validate data**: coming from each request:
    * Generating **automatic errors** returned to the client when the data is invalid.
* **Document** the API using OpenAPI:
    * which is then used by the automatic interactive documentation user interfaces.

		s.writeErrorResponse(w, err)
		return false
	}

	diskID := r.Form.Get(storageRESTDiskID)
	if diskID == "" {
		// Request sent empty disk-id, we allow the request
		// as the peer might be coming up and trying to read format.json
		// or create format.json
		return true
	}

	storedDiskID, err := s.getStorage().GetDiskID()
	if err != nil {
		s.writeErrorResponse(w, err)
		return false
	}

// so they are only valid until the next bufio read.
func readChunkLine(b *bufio.Reader) ([]byte, []byte, error) {
	buf, err := b.ReadSlice('\n')
	if err != nil {
		// We always know when EOF is coming.
		// If the caller asked for a line, there should be a line.
		switch err {
		case io.EOF:
			err = io.ErrUnexpectedEOF
		case bufio.ErrBufferFull:
			err = errLineTooLong
		}
		return nil, nil, err

```sh
firewall-cmd --reload
```

### iptables

For hosts with iptables enabled (RHEL, CentOS, etc), you can use `iptables` command to enable all traffic coming to specific ports. Use below command to allow
access to port 9000

```sh
iptables -A INPUT -p tcp --dport 9000 -j ACCEPT
service iptables restart
```

	p.diskID.Store(&id)
}

func (p *xlStorageDiskIDCheck) checkDiskStale() error {
	if *p.diskID.Load() == emptyDiskID {
		// For empty disk-id we allow the call as the server might be
		// coming up and trying to read format.json or create format.json
		return nil
	}
	storedDiskID, err := p.storage.GetDiskID()
	if err != nil {
		// return any error generated while reading `format.json`
		return err
	}