code: function validateConstraints(matchingConstraints) {
    if (matchingConstraints.callbackId &&
        !(isString(matchingConstraints.callbackId) || isRegExp(matchingConstraints.callbackId))) {
      return new TypeError('Callback ID must be a string or RegExp');
    }
  
    if (matchingConstraints.blockId &&
      !(isString(matchingConstraints.blockId) || isRegExp(matchingConstraints.blockId))) {
      return new TypeError('Block ID must be a string or RegExp');
    }
  
    if (matchingConstraints.actionId &&
      !(isString(matchingConstraints.actionId) || isRegExp(matchingConstraints.actionId))) {
      return new TypeError('Action ID must be a string or RegExp');
    }
  
    return false;
  }
docs: Validates general properties of a matching constraints object
  @param {Object} matchingConstraints - object describing the constraints on a callback
  @returns {Error|false} - a false value represents successful validation, otherwise an error to
  describe why validation failed.
  @private