When called with just the `key` argument, return a random field from the hash
value stored at `key`.

If the provided `count` argument is positive, return an array of **distinct
fields**. The array's length is either `count` or the hash's number of fields
(`HLEN`), whichever is lower.

If called with a negative `count`, the behavior changes and the command is
allowed to return the **same field multiple times**. In this case, the number of
returned fields is the absolute value of the specified `count`.

The optional `WITHVALUES` modifier changes the reply so it includes the
respective values of the randomly selected hash fields.

@return

@bulk-string-reply: without the additional `count` argument, the command returns
a Bulk Reply with the randomly selected field, or `nil` when `key` does not
exist.

@array-reply: when the additional `count` argument is passed, the command
returns an array of fields, or an empty array when `key` does not exist. If the
`WITHVALUES` modifier is used, the reply is a list fields and their values from
the hash.

@examples

```cli
HMSET coin heads obverse tails reverse edge null
HRANDFIELD coin
HRANDFIELD coin
HRANDFIELD coin -5 WITHVALUES
```

## Specification of the behavior when count is passed

When the `count` argument is a positive value this command behaves as follows:

- No repeated fields are returned.
- If `count` is bigger than the number of fields in the hash, the command will
  only return the whole hash without additional fields.
- The order of fields in the reply is not truly random, so it is up to the
  client to shuffle them if needed.

When the `count` is a negative value, the behavior changes as follows:

- Repeating fields are possible.
- Exactly `count` fields, or an empty array if the hash is empty (non-existing
  key), are always returned.
- The order of fields in the reply is truly random.