def increment(key, amount = 1, options = {})
      invoke(:increment, key) do |store|
        alter(store, key, amount, options)
      end
    end
def increment(key, amount = 1, options = {})
      invoke(:increment, key) do |store|
        alter(store, key, amount, options)
      end
    end
Increment a key in the store.

 If the key doesn't exist it will be initialized at 0. If the key exists
 but it isn't a Fixnum it will be coerced to 0.

 Note that this method does *not* use Redis' native `incr` or `incrby`
 commands. Those commands only work with number-like strings, and are
 incompatible with the encoded values Readthis writes to the store. The
 behavior of `incrby` is preserved as much as possible, but incrementing
 is not an atomic action. If multiple clients are incrementing the same
 key there will be a "last write wins" race condition, causing incorrect
 counts.

 If you absolutely require correct counts it is better to use the Redis
 client directly.

 @param [String] key Key for lookup
 @param [Fixnum] amount Value to increment by
 @param [Hash] options Optional overrides

 @example

   cache.increment('counter') # => 1
   cache.increment('counter', 2) # => 3