code: function Registry(opt_options) {
    if (!(this instanceof Registry)) {
      return new Registry(opt_options);
    }
    opt_options = opt_options || {};
  
    this.breakOnError = opt_options.breakOnError || false;
    this.depth = opt_options.depth || 10;
  
    // regex to match "$schema.*"
    this._match = /"\$id:[a-z0-9_-]*"/ig;
    // regex to escape strings for usage as regex
    this._escape = /[\-\[\]\/\{\}\(\)\*\+\?\.\\\^\$\|]/g;
  
    this.schemas = {};
  }
docs: The schema registry
  
  @param {?Object=} opt_options The registry configuration
  @constructor