code: function(constructor, desc){
          var name = constructor.name;
          this.assert(
              this.obj instanceof constructor
              , function(){ return 'expected ' + this.inspect + ' to be an instance of ' + name + (desc ? " | " + desc : "") }
              , function(){ return 'expected ' + this.inspect + ' not to be an instance of ' + name + (desc ? " | " + desc : "") });
          return this;
      }
docs: Assert instanceof.
  
  @param {Function} constructor
  @param {String} description
  @api public