…#13339)

I reviewed `XREAD` command syntax:
```
XREAD [COUNT count] [BLOCK milliseconds] STREAMS key [key ...] id [id ...]
```

Here’s the structure for `XREAD`:
```json
"arguments": [
            {
                "token": "COUNT",
                "name": "count",
                "type": "integer",
                "optional": true
            },
            {
                "token": "BLOCK",
                "name": "milliseconds",
                "type": "integer",
                "optional": true
            },
            {
                "name": "streams",
                "token": "STREAMS",
                "type": "block",
                "arguments": [
                    {
                        "name": "key",
                        "type": "key",
                        "key_spec_index": 0,
                        "multiple": true
                    },
                    {
                        "name": "ID",
                        "type": "string",
                        "multiple": true
                    }
                ]
            }
]
```

Now, consider the `HEXPIRE` syntax:
```
HEXPIRE key seconds [NX | XX | GT | LT] FIELDS numfields field [field ...]
```

Since the `FIELDS` token functions similarly to `STREAMS`, and given that `STREAMS` is defined as a block, I believe the `FIELDS` in `hepxire` should also be defined as a block.