DeleteRange deletes the given range from the key-value store. A delete request increments the revision of the key-value store and generates a delete event in the event history for every deleted key.
key is the key, in bytes, to put into the key-value store.
If prev_kv is set, etcd gets the previous key-value pair before changing it. The previous key-value pair will be returned in the put response.
range_end is the upper bound on the requested range [key, range_end). If range_end is '\0', the range is all keys >= key. If the range_end is one bit larger than the given key, then the range requests get the all keys with the prefix (the given key). If both key and range_end are '\0', then range requests returns all keys. the key is encoded with base64. type bytes. NOTE: If range_end is not given, the request only looks up key.