code: function(mediator, fileClient) {
      //If there is already a set of subscribers set up, then don't subscribe again.
      if (fileSubscribers) {
        return fileSubscribers;
      }
  
      fileSubscribers = new MediatorTopicUtility(mediator);
      fileSubscribers.prefix(CONSTANTS.TOPIC_PREFIX).entity(CONSTANTS.FILES_ENTITY_NAME);
  
      //Setting up subscribers to the file topics.
      _.each(CONSTANTS.TOPICS, function(topicName) {
        if (topicHandlers[topicName]) {
          fileSubscribers.on(topicName, topicHandlers[topicName](fileSubscribers, fileClient));
        }
      });
      return fileSubscribers;
    }
docs: Initialisation of all the topics that this module is interested in.
  @param {Mediator}                   mediator
  @param {FileMediatorService}    fileClient
  @returns {Topics|exports|module.exports|*}