code: function data(key, value) {
      if (string(key)) {
        // Set `key`.
        if (arguments.length === 2) {
          assertUnfrozen('data', frozen)
  
          namespace[key] = value
  
          return processor
        }
  
        // Get `key`.
        return (own.call(namespace, key) && namespace[key]) || null
      }
  
      // Set space.
      if (key) {
        assertUnfrozen('data', frozen)
        namespace = key
        return processor
      }
  
      // Get space.
      return namespace
    }
docs: Data management.  Getter / setter for processor-specific informtion.