whole_func_string: function (key, done) {
        var val = null;
        if(cache.hasOwnProperty(key)) {
          val = cache[key];
        }
        return done(null, val);
      }
func_code_string: function (key, done) {
        var val = null;
        if(cache.hasOwnProperty(key)) {
          val = cache[key];
        }
        return done(null, val);
      }
func_documentation_string: Attempt to retrieve the set value for the given key.
  @param {string} key
  @param {function} done