code: function assert(condition, errorMessage) {
    var error = processCondition(condition, errorMessage);
    if (typeof error === 'string') {
      throw new Error(error);
    }
  }
docs: Throws an error if the boolean passed to it evaluates to false.
  To be used like this:
  assert(myDate !== undefined, "Date cannot be undefined.");
  @api public
  @method assert
  @param  {Boolean} condition - Result of the evaluated condition
  @param  {String} errorMessage - Message explainig the error in case it is thrown
  @return void