Use Redis namespaces for caching stuff.

app/models/arg_name.rb

@@ -1,12 +1,12 @@
 # Support class for Fragment. Please see fragment.rb for documentation.
 class ArgName < ApplicationRecord
   EXPIRY = Rails.env.test? ? 1.second : 2.hours
-  KEY    = "arg_names/%s"
+  KEY = "arg_names:%s"
 
   validates_uniqueness_of :value
 
   has_many :primitive_pairs, autosave: true
-  has_many :standard_pairs,  autosave: true
+  has_many :standard_pairs, autosave: true
 
   def self.cached_by_value(v)
     key = KEY % v

app/models/kind.rb

@@ -1,7 +1,7 @@
 # Support class for Fragment. Please see fragment.rb for documentation.
 class Kind < ApplicationRecord
   EXPIRY = Rails.env.test? ? 1.second : 2.hours
-  KEY    = "kinds/%s"
+  KEY = "kinds:%s"
   has_many :nodes
 
   def self.cached_by_value(v)