code: function PatternModule(agent, options) {
    this.agent = agent;
    this.stopPropagation = options && options.stopPropagation || false;
    this.receiveOriginal = agent._receive;
    this.listeners = [];
  }
docs: Create a pattern listener onto an Agent.
  A new handler is added to the agents _receiver function.
  Creates a Pattern instance with functions `listen` and `unlisten`.
  @param {Agent} agent
  @param {Object} [options]   Optional parameters. Can contain properties:
  - stopPropagation: boolean
  When false (default), a message
  will be delivered at all
  matching pattern listeners.
  When true, a message will be
  be delivered at the first
  matching pattern listener only.