PSUBSCRIBE pattern [pattern ...]
Time complexity: O(N) where N is the number of patterns the client is already subscribed to.
Subscribes the client to the given patterns.
Supported glob-style patterns:
hxllo(matches a single character)
heeeello(matches a sequence of characters, possibly empty)
hillo(matches a single character from the list)
\ to escape special characters if you want to match them verbatim.