def register(name, mod, options)
      elements[name] = plugin_type.new(mod, options)
    end
def register(name, mod, options)
      elements[name] = plugin_type.new(mod, options)
    end
Assign a plugin to this environment registry

 @param [Symbol] name The registered plugin name
 @param [Module] mod The plugin to register
 @param [Hash] options optional configuration data

 @api private