Reset a Redis Cluster node, in a more or less drastic way depending on the reset
type, that can be **hard** or **soft**. Note that this command **does not work
for masters if they hold one or more keys**, in that case to completely reset a
master node keys must be removed first, e.g. by using `FLUSHALL` first, and then
`CLUSTER RESET`.

Effects on the node:

1. All the other nodes in the cluster are forgotten.
2. All the assigned / open slots are reset, so the slots-to-nodes mapping is
   totally cleared.
3. If the node is a replica it is turned into an (empty) master. Its dataset is
   flushed, so at the end the node will be an empty master.
4. **Hard reset only**: a new Node ID is generated.
5. **Hard reset only**: `currentEpoch` and `configEpoch` vars are set to 0.
6. The new configuration is persisted on disk in the node cluster configuration
   file.

This command is mainly useful to re-provision a Redis Cluster node in order to
be used in the context of a new, different cluster. The command is also
extensively used by the Redis Cluster testing framework in order to reset the
state of the cluster every time a new test unit is executed.

If no reset type is specified, the default is **soft**.

@return

@simple-string-reply: `OK` if the command was successful. Otherwise an error is
returned.